Building Acoustics Demystified - Introduction to NRC, STC, and IIC Ratings

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Welcome to Catalyst Conversations, the podcast
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that brings you real world stories and solutions
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from a wide variety of acoustic experts. Each
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episode, we'll dive into a different topic from
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the world of acoustics, such as architectural
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and industrial noise control, seismic and vibration
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restraint, acoustical testing, or innovative
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design and engineering of sound control products.
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Our experts have decades of experience in this
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space and are eager to share their expertise
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with you. Join us in making the world a quieter
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place. Hello and welcome to Catalyst Conversations.
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My name is Adam Ritzak and I am a Content Marketing
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Manager at Catalyst where I help to moderate
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our podcast discussions. Before we dive into
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this episode, we're excited to share a new event
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To learn more and secure your registration, please
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visit catalystacoustics .com slash connect. We
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hope to see you there. Back to the focus of today's
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episode, where Eric Wolfram from Riverbank Acoustical
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Laboratories will lead this deep dive on the
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key concepts in building acoustics and how occupants
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experience each. Eric will cover several key
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topics in the space, including an explanation
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of the most common ASTM classifications cited
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in building codes and architectural specifications,
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insight into the physical properties of materials
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that contribute to real performance in each of
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these categories, and an introduction to the
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growing field of architectural acoustics. So
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now, We'll turn it over to Eric for this episode.
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My name is Eric Wolfram. I'm the laboratory manager
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of Riverbank Acoustical Laboratories in Geneva,
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Illinois. And I also currently serve as the chair
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of the ASTM E33 committee, although... So this
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presentation is recorded in 2025, and by the
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end of 2025, I'll be term limited. So first,
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just a short explanation of what Riverbank Acoustical
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Laboratories is. We were founded in 1918, so
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over 100 years ago. The facility and lab operation
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was funded by this gentleman, George Fabian,
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and the lab chamber was designed by Wallace Clemens
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Sabin. We have a whole presentation on that history
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on our YouTube channel, so if you would like
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to go deep into our history, check that out.
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Today, we are accredited by NAVLAB as an ISO
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17025 laboratory, and we perform about 26 different
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testing standards. We average about 1 ,200 tests
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per year for over 300 different organizations.
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However, most of our tests are... ASTM C423,
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NRC, ASTM E90, STC E492, which is IIC, and sound
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power testing. So the main goal today, the main
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thing I want you to walk away from this presentation
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with is an understanding of these three kind
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of basic concepts in building acoustics, what
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they mean, and how they're tested, and what the
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test results mean. relative to your experience
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of a building so first the first term is sound
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absorption and when we use this term sound absorption
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we're referring to the ability of a material
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to revert reduce reverberation time within a
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space now don't worry i'm going to go give you
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some good examples and deeper explanation on
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each of these topics so but just to start Remember,
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sound absorption is referring to the ability
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of materials to reduce sound reflections and
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reverberation within a space. Airborne sound
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insulation, or more specifically, sound transmission
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loss, is how we describe in building acoustics,
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it's how we describe the ability of a wall or
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barrier or window or door, anything that's intended
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to block sound from one room. through to the
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other. And then finally, impact sound transmission.
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And there are different ways this kind of test
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data can be used, but the standard had in mind
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when it was developed and I think is still most
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frequently used around the issue of footfall
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noise in multifamily housing or hotels. So the
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question of how well do I hear someone walking
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on the floor above. So for each of these general
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properties of materials, ASTM has classifications.
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So for sound absorption, the classification that's
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most commonly used is noise reduction coefficient
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or NRC. That's the rating you're most likely
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to see on things like acoustical ceiling tiles,
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wall panels, et cetera. For airborne sound insulation,
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again, the ability to block sound, you're going
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to see sound transmission class or STC ratings.
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And then third, that reduction of footfall noise
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condition, you're going to see IIC ratings or
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impact insulation class ratings. As you're beginning
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your journey in acoustics, it is intuitive that
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all these things might be similar. and that the
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properties of materials that are good for one
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must be good for the other right and that they're
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somewhat interchangeable uh very wrong so um
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they're in some ways often opposite different
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types of materials are sometimes good with nrc
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and bad with stc or may have a good stc but a
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poor iic this is common all over the place so
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there is from a physics point of view there is
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some overlap But it's really better to think
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of these as three completely isolated properties,
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three ratings, which have nothing to do with
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each other. And if your question is in regards
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to STC, that NRC does not answer your question.
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So our lab and labs in general are built to control
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all sorts of properties and paths that sound
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might take. to be able to identify these three
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classifications for a specific material all right
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so the first property that we'll look at in depth
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is sound absorption and remember this is a property
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of materials or property related to interior
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of space so its main the main consideration with
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sound absorption is reverberation So one could
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think of the sound absorption performance of
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a material as its ability to reduce reverberation.
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So what is reverberation? Well, within an enclosed
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space, hard surfaces will tend to reflect sound
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waves. Now this diagram on the right here. This
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kind of gives like a simplified explanation of
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what's happening with a sound reflection. Now,
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generally, sound waves reflect off of a surface
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where the angle of incidence equals the angle
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of reflection. So they have sort of a predictable
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reflection pattern similar to, let's say, like
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a billiard ball, right? However, in reality,
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um and we we often in acoustics create these
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demonstrations with kind of focused sound waves
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coming out almost like a laser towards the wall
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or a single line towards the wall the reality
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is that sound waves are incredibly messy and
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not only is the speaker creating a very uh sound
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level at different positions around the speaker
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which is all coming out in different directions
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but those waves as they propagate towards the
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wall are constantly dispersing so the sound is
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sort of flowing in all directions um so as all
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these sound waves are flowing towards the wall
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and reflecting in all directions it creates this
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this echo right this reverberation within the
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space We measure that in terms of the reverberation
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time, which is generally the time it takes that
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sound field to decay 60 decibels after the source
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is interrupted. I'm going to give you a couple
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examples here of different spaces or sounds recorded
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in different spaces and how the room itself affects
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the sound. So believe it or not. In these first
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impulse sounds, this is the exact same device,
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the exact same noise source recorded from the
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exact same distance from the same microphone
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at the same level. The only thing that's changed
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is the room that this recording is made in. So
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this first recording will be of an impulsive
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sound in an anechoic or dead, we call it dead
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environment. Actually, that's not really an acoustics
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term. That's like an audio guy term, audio person
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term. So I'll play it a couple times for you
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because it's real quick. So listen, you hear
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the metallic clarity and detail of this object.
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This is actually a 1950s pop gun that some of
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you have seen in our lab. And you hear like the
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very clear detail of the mechanism. All right.
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Now we'll go to, again, same distance, same object,
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just only thing that's different is the room
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it's recorded in. so you hear you lost all the
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detail of the mechanism and you hear this long
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reverberant tail this is the recording was made
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in our room zero our main diffuse field chamber
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so this reverberation was very important to a
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space especially like a critical listening space
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but really any space where humans are occupying
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and talking and and existing in so in most cases
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reverberation is like a type of noise it's detrimental
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to the purpose of the space now i have to be
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careful because there are some very important
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counter examples to that and which some of the
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acquisitions are already shuffling in their seats
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like no it's not okay so something like a concert
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hall especially a concert hall that is intended
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for choral music or orchestra having a well -balanced
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reverberant sound field is very important to
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the musician performance and the experience of
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the listeners in that space it's part of the
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experience it's important even then there's a
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limit like not unlimited reverberation and even
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the six second example is too long but you know
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a good well -balanced reverberation tail probably
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the upper end of the you know if there's a spectrum
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of things that want reverberation versus don't
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want reverberation i would say on one end of
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the spectrum would be uh pipe organ music from
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like a like a cathedral or a classical worship
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space and um like gregorian chant those would
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love um a lot of reverberation now on the other
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end of the spectrum would be something like a
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movie theater, where you don't want this echo
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and this echo would interfere with the purpose
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and function of that space. So this here is some
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speech recorded in a dead environment. in order
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that hearing may be good in any auditorium it
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is necessary that the sounds should be sufficiently
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loud that the simultaneous components of a complex
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sound should maintain their proper relative intensities
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and that the successive sounds in rapidly moving
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articulation either of speech or music should
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be clear and distinct free from each other and
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from extraneous noises These three are the necessary,
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as they are the entirely sufficient, conditions
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for good hearing. Now, same sound source, same
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distance, only thing that's changed is the room.
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So, in fact, I'm realizing I should have played
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it the other way around because you have a clue.
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You already knew what the word said. But if you
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didn't know what the word said there, you'd have
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a real hard time making out speech. So that reverberation
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is it's detrimental to your ability to understand
00:13:55.120 --> 00:13:58.279
speech in that environment. the field of acoustics
00:13:58.279 --> 00:14:01.399
or building acoustics started with this this
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equation right here this is the wallace saban
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equation and this was developed by a gentleman
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named wallace saban and he was a professor at
00:14:10.000 --> 00:14:13.259
harvard that derived this equation and basically
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started the whole field of architectural acoustics
00:14:15.700 --> 00:14:20.120
it's a very simple equation which allowed us
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to allow people at the time to predict reverberation
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time and actually this equation still used today
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it has its place and purpose in the field of
00:14:31.870 --> 00:14:34.490
acoustics today although there are other alternative
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equations for other types of environments and
00:14:37.330 --> 00:14:40.230
there are sophisticated acoustical modeling programs
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which will allow you to do more with more detail
00:14:44.899 --> 00:14:47.840
however the the validity of this equation still
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holds so basically we're able to predict the
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reverberation time of a space knowing the air
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volume and the total sabins present in a room
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sabins is the unit of sound absorption what is
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a sabin uh we have different ways of explaining
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this and like a lot of physics metaphors um they
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can be very helpful but also have their limits
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and that at the very high end of understanding
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the metaphor is actually counter to understanding
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so um we'll we'll try our best here so i think
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that wallace himself and at least very early
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on the the explanation of a saving was that one
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saving was like one square foot of open window
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this this wallace sabin equation is the basis
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for the astm c423 test method so a variation
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of this equation which is solved for the total
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savings and with a adjustment to correct for
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the speed of sound in that chamber is used so
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how how we run this test is we will test the
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reverberation time in the empty space and then
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we will install the material under test and then
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measure the reverberation times again using this
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equation we're able to determine the total sabins
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of absorption in the empty chamber and the total
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sabins of absorption in the chamber when the
00:16:28.879 --> 00:16:32.120
material is installed if you subtract the empty
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chamber then you're left with a quantity of savings
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attributed just to the sample under test so a
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area a sound absorption area that has been added
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to the chamber just from the adding this device
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or object or whatever it is under test if the
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sample under test is a flat two -dimensional
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material then we can determine the sabins per
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square feet of that material. So in this example,
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we have an eight foot by nine foot rectangular
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patch of material, which is 72 square feet. So
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if we measured 72 sabins of sound absorption
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and we have 72 square feet of material, then
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we would have one sabin per square foot. in architectural
00:17:33.269 --> 00:17:36.490
acoustics we call that a sound absorption coefficient
00:17:36.490 --> 00:17:45.529
so 1 .0 now that term is used tech is not technically
00:17:45.529 --> 00:17:47.970
correct it is not actually an energy absorption
00:17:47.970 --> 00:17:51.750
coefficient um however that's the way you know
00:17:51.750 --> 00:17:54.549
this we we have used that term in this industry
00:17:54.549 --> 00:17:57.250
it's very traditional so sound absorption coefficient
00:17:57.250 --> 00:18:02.339
and for the most part 1 .0 is 100 per seen as
00:18:02.339 --> 00:18:05.579
100 absorptive but really what it means is you
00:18:05.579 --> 00:18:09.339
have one sabin per square foot now if you have
00:18:09.339 --> 00:18:12.200
an nr a sound absorption coefficient of 0 .5
00:18:12.200 --> 00:18:16.200
that's sometimes seen as being a 50 absorption
00:18:16.200 --> 00:18:21.420
which is you know approximately correct um the
00:18:21.420 --> 00:18:25.349
where it breaks down is it is possible to achieve
00:18:25.349 --> 00:18:28.750
it's actually a possible in common to achieve
00:18:28.750 --> 00:18:32.849
rates of absorption greater than one saving per
00:18:32.849 --> 00:18:36.230
square foot so greater absorption coefficients
00:18:36.230 --> 00:18:40.230
greater than 1 .0 and this is not alarming or
00:18:40.230 --> 00:18:42.329
anything like that it's it's just the nature
00:18:42.329 --> 00:18:45.089
of the test and i'll maybe someday we'll do a
00:18:45.089 --> 00:18:48.190
presentation just on that subject but yes it's
00:18:48.190 --> 00:18:50.109
possible to have absorption coefficient greater
00:18:50.109 --> 00:18:53.750
than one So what is NRC? NRC is the classification
00:18:53.750 --> 00:19:00.549
or the single number rating for a test with a
00:19:00.549 --> 00:19:05.410
variable performance across different frequencies.
00:19:05.529 --> 00:19:08.369
So what that means is this is an example of a
00:19:08.369 --> 00:19:10.769
test result for a sound absorption material.
00:19:12.750 --> 00:19:17.329
This is actually pretty good representation of,
00:19:17.390 --> 00:19:20.009
let's say, a two inch thick sound absorption
00:19:20.009 --> 00:19:23.970
core, something like that, just generally. And
00:19:23.970 --> 00:19:26.430
you see the performance is very different at
00:19:26.430 --> 00:19:31.769
different frequencies. So above 300 hertz, you're
00:19:31.769 --> 00:19:35.849
above 1 .0 for most of the range above 300 hertz,
00:19:36.029 --> 00:19:39.349
but then the performance drops at lower frequencies.
00:19:39.369 --> 00:19:42.890
So it's harder to absorb. lower frequencies generally
00:19:42.890 --> 00:19:46.869
this is sort of complicated right and if you're
00:19:46.869 --> 00:19:49.549
marketing acoustical materials you you don't
00:19:49.549 --> 00:19:51.630
want to have to explain well our material has
00:19:51.630 --> 00:20:00.029
a 0 .45 at 160 hertz and 1 .1 at a thousand hertz
00:20:00.029 --> 00:20:03.930
you just want a single number that can be used
00:20:03.930 --> 00:20:07.150
in a broad way to compare material a to material
00:20:07.150 --> 00:20:12.099
b so the traditional or historic rating for that
00:20:12.099 --> 00:20:14.500
single number was the noise reduction coefficient
00:20:14.500 --> 00:20:20.720
or nrc the definition of nrc is it is the average
00:20:20.720 --> 00:20:26.500
of the sound absorption coefficients at 250 500
00:20:26.500 --> 00:20:32.900
1000 and 2000 hertz rounded to the nearest 0
00:20:32.900 --> 00:20:36.680
.05 now some of you technical people may have
00:20:36.680 --> 00:20:40.130
some questions yes so there are a number of problems
00:20:40.130 --> 00:20:43.829
with this um and this is not the way the industry
00:20:43.829 --> 00:20:46.549
would do things if it if it was to create a number
00:20:46.549 --> 00:20:49.390
today a single number rating today we have to
00:20:49.390 --> 00:20:52.630
remember this goes back to pre -computers where
00:20:52.630 --> 00:20:55.150
everything had to be calculated by hand and just
00:20:55.150 --> 00:20:58.450
a different understanding of when to round and
00:20:58.450 --> 00:21:02.609
how today more recently they developed a sound
00:21:02.609 --> 00:21:07.140
absorption average or saa This takes a range
00:21:07.140 --> 00:21:09.700
of all the one -third octave bands from 200 to
00:21:09.700 --> 00:21:14.240
2 ,500 and rounds to the nearest 0 .01. At ASTM,
00:21:14.259 --> 00:21:15.799
we believe this is more technically correct.
00:21:16.440 --> 00:21:18.940
It's also the currently defined single number
00:21:18.940 --> 00:21:25.200
rating. However, most of the industry still references
00:21:25.200 --> 00:21:29.480
NRC ratings pretty broadly. So what are the properties
00:21:29.480 --> 00:21:34.329
of material that contribute to? Sound absorption
00:21:34.329 --> 00:21:39.089
performance. Most sound absorption materials
00:21:39.089 --> 00:21:43.970
are porous or fibrous media. So that porosity
00:21:43.970 --> 00:21:47.049
and fibrous material is very important. So as
00:21:47.049 --> 00:21:51.130
sound flows through it, energy is lost as it
00:21:51.130 --> 00:21:53.450
moves through all that material. It's lost in
00:21:53.450 --> 00:21:55.990
the pockets and all the different transfers of
00:21:55.990 --> 00:21:59.670
air to material to air. Thickness is very important
00:21:59.670 --> 00:22:03.250
for this type of absorber. um so it takes about
00:22:03.250 --> 00:22:06.789
two inches of porous fibrous material of sufficient
00:22:06.789 --> 00:22:10.990
density to get an nrc of 1 .0 with no air space
00:22:10.990 --> 00:22:16.029
behind it density does matter maybe less so than
00:22:16.029 --> 00:22:18.329
thickness but density is important and too much
00:22:18.329 --> 00:22:21.069
density can actually start to reduce performance
00:22:21.069 --> 00:22:23.829
as well so there's a sweet spot you know somewhere
00:22:23.829 --> 00:22:27.390
in the five to eight or nine pounds per cubic
00:22:27.390 --> 00:22:34.200
feet where materials are very effective if you'll
00:22:34.200 --> 00:22:36.500
know you'll often notice that materials some
00:22:36.500 --> 00:22:38.380
materials are installed with a deep air space
00:22:38.380 --> 00:22:41.059
behind them for example acoustical ceiling tile
00:22:41.059 --> 00:22:45.960
that's that air space is a way to cheat basically
00:22:45.960 --> 00:22:50.019
in a good way and get more performance out of
00:22:50.019 --> 00:22:52.420
a material than it should be allowed based on
00:22:52.420 --> 00:22:58.000
its thickness and this this is allowed You are
00:22:58.000 --> 00:23:02.240
allowed to test with an airspace if the material
00:23:02.240 --> 00:23:04.220
is typically installed with an airspace. So,
00:23:04.299 --> 00:23:06.779
for example, acoustical ceiling tiles. And there
00:23:06.779 --> 00:23:09.559
are a number of different mounting methods which
00:23:09.559 --> 00:23:12.180
define different types of airspaces. But they
00:23:12.180 --> 00:23:16.099
have a very significant impact on the performance
00:23:16.099 --> 00:23:19.700
of the material. And therefore, the results are
00:23:19.700 --> 00:23:24.539
really specific to that mounting. The surface
00:23:24.539 --> 00:23:28.640
is very critical. that surface needs to be air
00:23:28.640 --> 00:23:31.619
permeable so that the sound waves flow through
00:23:31.619 --> 00:23:35.420
the surface and are absorbed by the core yes
00:23:35.420 --> 00:23:39.039
so painting the surface of an acoustical wall
00:23:39.039 --> 00:23:42.279
panel especially a very thick latex paint multiple
00:23:42.279 --> 00:23:45.980
coats with a big woolen roller yes regardless
00:23:45.980 --> 00:23:48.519
of what everyone to anyone tells you that will
00:23:49.160 --> 00:23:52.920
reduce the effective nrc rating there are products
00:23:52.920 --> 00:23:55.779
out there that are tinted and painted by the
00:23:55.779 --> 00:23:58.519
manufacturer and those companies put a lot of
00:23:58.519 --> 00:24:02.319
engineering into making that surface work well
00:24:02.319 --> 00:24:06.339
so that they when they test it it's it is painted
00:24:06.339 --> 00:24:09.480
and coated and achieves the exact nrc that's
00:24:09.480 --> 00:24:11.960
actually a difficult engineering problem for
00:24:11.960 --> 00:24:14.119
acoustical product manufacturers to get that
00:24:14.119 --> 00:24:16.910
just right There's another category we won't
00:24:16.910 --> 00:24:20.049
go into too much, which would be like tunes diaphragm
00:24:20.049 --> 00:24:22.910
absorbers. So it is possible to make a sound
00:24:22.910 --> 00:24:25.589
absorber that has a resonance. Typically, these
00:24:25.589 --> 00:24:27.890
are effective at certain frequencies, though,
00:24:27.970 --> 00:24:32.029
and not broadband. Next up, sound transmission
00:24:32.029 --> 00:24:35.089
loss. This is, again, referring to the ability
00:24:35.089 --> 00:24:38.829
of walls to block sound. Sound transmission loss
00:24:38.829 --> 00:24:43.049
measures how well a wall will prevent you from
00:24:43.049 --> 00:24:46.069
hearing your neighbor. through that wall in a
00:24:46.069 --> 00:24:49.130
condominium. So airborne sounds, human voice,
00:24:49.410 --> 00:24:53.509
television, a dog barking, these sorts of things
00:24:53.509 --> 00:24:56.390
we would consider airborne sound. So what are
00:24:56.390 --> 00:25:00.410
the properties of a material that generally give
00:25:00.410 --> 00:25:03.849
higher sound transmission loss or a better ability
00:25:03.849 --> 00:25:08.190
to block airborne sounds? Most fundamentally
00:25:08.190 --> 00:25:14.119
is mass. So generally an almost Very broadly,
00:25:14.259 --> 00:25:19.059
heavier is generally better. So heavier materials
00:25:19.059 --> 00:25:23.980
are more massive and therefore it takes more
00:25:23.980 --> 00:25:27.099
energy to make them move or to make them vibrate.
00:25:28.559 --> 00:25:32.240
Limpness, so this one's often counterintuitive
00:25:32.240 --> 00:25:33.799
and we'll hit on this in a couple of different
00:25:33.799 --> 00:25:38.779
ways. But stiffness works against you. generally
00:25:38.779 --> 00:25:42.519
for sound transmission loss so stiffness is not
00:25:42.519 --> 00:25:45.339
your friend for sound transmission loss generally
00:25:45.339 --> 00:25:49.559
and if you think about it lead is kind of a classic
00:25:49.559 --> 00:25:53.440
legendary material used in recording studios
00:25:53.440 --> 00:25:56.579
from the mid -century on you know creating sound
00:25:56.579 --> 00:25:59.900
isolation and lead what does lead have it's very
00:25:59.900 --> 00:26:04.859
massive very heavy and it's also very limp So
00:26:04.859 --> 00:26:07.240
it was sort of a perfect ideal material. Now,
00:26:07.299 --> 00:26:11.660
for various reasons, people work with lead much
00:26:11.660 --> 00:26:18.099
less than they did in the 1950s. So further air
00:26:18.099 --> 00:26:21.779
tightness, small gaps will kill your STC performance
00:26:21.779 --> 00:26:25.880
much more than you might think. And a good example
00:26:25.880 --> 00:26:29.160
I give of this is, so you're in your car, you're
00:26:29.160 --> 00:26:32.079
driving in your car on the highway. If you open
00:26:32.079 --> 00:26:35.250
your window all the way open, You hear all the
00:26:35.250 --> 00:26:40.349
air turbulence noise and tire noise and everyone's
00:26:40.349 --> 00:26:42.230
engine and everything just coming clear through
00:26:42.230 --> 00:26:45.650
the window, right? If you close that window halfway,
00:26:46.410 --> 00:26:49.329
it really, I mean, it sounds almost the same,
00:26:49.430 --> 00:26:53.049
right? Three quarters. Okay, now you may have
00:26:53.049 --> 00:26:58.369
noticed some change, but it's still very loud.
00:26:58.509 --> 00:27:03.339
Seven eighths, still very loud. It is only when
00:27:03.339 --> 00:27:08.500
the window fully seals into the top of the door,
00:27:08.539 --> 00:27:10.700
into the seal, where you get that kind of almost
00:27:10.700 --> 00:27:16.259
airtight seal, that's when the sound sucks away
00:27:16.259 --> 00:27:19.700
and is gone, right? So you had to achieve that
00:27:19.700 --> 00:27:23.299
airtightness in the window to achieve the maximum
00:27:23.299 --> 00:27:28.549
possible STC out of that window. Next up, damping.
00:27:28.670 --> 00:27:32.329
This is important. This is a critical factor
00:27:32.329 --> 00:27:36.910
of how the wall is performing. It's not always
00:27:36.910 --> 00:27:39.890
thought of in as much detail as the others, but
00:27:39.890 --> 00:27:42.930
this is basically friction in the vibrating system,
00:27:43.230 --> 00:27:46.789
whatever it is. So basically dissipating energy
00:27:46.789 --> 00:27:50.730
in that vibrating system. And then finally, cavity
00:27:50.730 --> 00:27:53.450
absorption. So if you think of this acoustic
00:27:53.450 --> 00:27:59.119
guitar, it's... the effect of that wood body
00:27:59.119 --> 00:28:02.059
on the guitar when the string is played is that
00:28:02.059 --> 00:28:05.660
it kind of amplifies or it resonates in a way
00:28:05.660 --> 00:28:10.200
that that brings that energy enhances the the
00:28:10.200 --> 00:28:13.819
sound right you don't want that you do want that
00:28:13.819 --> 00:28:16.019
with a guitar but you don't want that with a
00:28:16.019 --> 00:28:19.460
wall assembly so imagine if you stuffed the body
00:28:19.460 --> 00:28:22.440
of that acoustic guitar with fiberglass or mineral
00:28:22.440 --> 00:28:26.890
fiber insulation then played it it would be totally
00:28:26.890 --> 00:28:29.970
dead you probably barely hear the strings right
00:28:29.970 --> 00:28:36.589
so that's that's basically what absorption does
00:28:36.589 --> 00:28:40.049
within a wall cavity it it reduces the resonance
00:28:40.049 --> 00:28:43.930
of that hollow cavity in the wall so it's very
00:28:43.930 --> 00:28:47.390
important to note that stc is a system performance
00:28:47.390 --> 00:28:50.130
and not a material performance what we mean is
00:28:51.579 --> 00:28:54.099
You don't have an STC rating for each of the
00:28:54.099 --> 00:28:57.099
components of a wall. You have an STC rating
00:28:57.099 --> 00:29:02.799
for the sum total of the wall or the window or
00:29:02.799 --> 00:29:07.559
any other acoustic system. So when you're thinking
00:29:07.559 --> 00:29:11.039
about systems or wall systems or doors or windows
00:29:11.039 --> 00:29:14.420
for sound transmission laws for STC, you want
00:29:14.420 --> 00:29:18.500
your system to be more like the 1970s Cadillac,
00:29:18.599 --> 00:29:24.900
which was heavy. floating and airtight so isolated
00:29:24.900 --> 00:29:27.720
suspension keeps the vibration of the road out
00:29:27.720 --> 00:29:31.299
of the body of the vehicle soft floating suspension
00:29:31.299 --> 00:29:34.579
and a really massive vehicle that took a lot
00:29:34.579 --> 00:29:38.460
of energy to make move and then airtight enclosed
00:29:38.460 --> 00:29:41.940
cabin which kind of blocked out the outside world
00:29:41.940 --> 00:29:45.180
right so that's the way you want to think for
00:29:45.180 --> 00:29:46.920
wall assembly you want your wall assembly to
00:29:46.920 --> 00:29:49.890
be more like the Cadillac and not like the go
00:29:49.890 --> 00:29:53.650
-kart right the go -kart is very very light very
00:29:53.650 --> 00:29:58.529
stiff and open so what does this mean for the
00:29:58.529 --> 00:30:03.109
wall assembly generally more layers is better
00:30:03.109 --> 00:30:08.490
adding mass of the gypsum board will improve
00:30:08.490 --> 00:30:11.769
generally up to a point the performance of the
00:30:11.769 --> 00:30:14.569
wall assembly and there are certain materials
00:30:14.569 --> 00:30:17.920
that are made to be lightweight consider that
00:30:17.920 --> 00:30:22.519
that lightweight alternative may affect your
00:30:22.519 --> 00:30:29.099
STC rating. So stiffness is, again, very critical
00:30:29.099 --> 00:30:33.440
as well. And sometimes counterintuitive. So lighter
00:30:33.440 --> 00:30:37.759
or thinner steel is actually better for STC.
00:30:37.880 --> 00:30:41.059
So think of it as the steel is lighter, it's
00:30:41.059 --> 00:30:44.109
more flexible. And the very light gauge steel
00:30:44.109 --> 00:30:47.549
is almost like a resilient. If you hold it, you
00:30:47.549 --> 00:30:50.190
can almost crush it in your hand. It's very resilient
00:30:50.190 --> 00:30:55.849
on the very light gauge steel. And then on the
00:30:55.849 --> 00:30:58.130
other end of the spectrum, maybe let's say like
00:30:58.130 --> 00:31:01.170
a two by four wood stud is very, very rigid,
00:31:01.349 --> 00:31:06.529
right? Very stiff. So the same gypsum board on
00:31:06.529 --> 00:31:09.430
both sides, the same insulation in the cavity.
00:31:10.539 --> 00:31:17.160
and the same spacing and fasteners, you could,
00:31:17.299 --> 00:31:21.359
or I should say tighter spacing and tighter screw
00:31:21.359 --> 00:31:26.799
pattern could range from STC 50 on a single layer
00:31:26.799 --> 00:31:32.119
gypsum board wall with really favorable framing
00:31:32.119 --> 00:31:39.700
conditions down to STC 3637. on the same gypsum
00:31:39.700 --> 00:31:43.740
board the same materials but more rigid framing
00:31:43.740 --> 00:31:51.720
so again a wider stud spacing is generally better
00:31:51.720 --> 00:31:55.920
for stc so like 24 inches on center will generally
00:31:55.920 --> 00:32:00.380
perform better than 16 inches on center and then
00:32:00.380 --> 00:32:04.740
a wider fastener spacing will generally perform
00:32:04.740 --> 00:32:09.160
better for stc so tighter screws You know, the
00:32:09.160 --> 00:32:11.119
contractor may think they're doing an extra good
00:32:11.119 --> 00:32:12.599
job because the wall is really important. We're
00:32:12.599 --> 00:32:15.460
going to put a lot more screws in. That actually
00:32:15.460 --> 00:32:18.099
can hurt your STC very significantly sometimes.
00:32:18.440 --> 00:32:21.940
So now some of you are already thinking, okay,
00:32:22.039 --> 00:32:24.119
this is a problem because all the things we just
00:32:24.119 --> 00:32:27.119
mentioned are not possible in my building because
00:32:27.119 --> 00:32:30.259
we need that wall to be structural and we need
00:32:30.259 --> 00:32:35.190
it to pass fire requirements. the good news is
00:32:35.190 --> 00:32:38.630
that when your wall needs to be stiff for for
00:32:38.630 --> 00:32:41.450
those reasons there are other alternative products
00:32:41.450 --> 00:32:44.710
that are able to reintroduce that flexibility
00:32:44.710 --> 00:32:47.029
underneath the gypsum board and that's where
00:32:47.029 --> 00:32:50.609
like resilient channel or isolation clips come
00:32:50.609 --> 00:32:56.150
up so so again a single layer 5 8 type x gypsum
00:32:56.150 --> 00:33:00.410
board on both sides of a stud uh stud wall with
00:33:00.410 --> 00:33:02.970
with the same insulation in the cavity that could
00:33:02.970 --> 00:33:07.710
range from stc 37 to stc 50 just depending on
00:33:07.710 --> 00:33:13.589
on these these factors so um and then finally
00:33:13.589 --> 00:33:17.339
air tightness in the lab we will caulk the track
00:33:17.339 --> 00:33:20.160
to the test frame so that there's no path of
00:33:20.160 --> 00:33:23.180
leakage around the test frame and then after
00:33:23.180 --> 00:33:26.359
the gypsum board is installed one we isolate
00:33:26.359 --> 00:33:28.819
the gypsum board a small amount from the test
00:33:28.819 --> 00:33:32.140
frame and then we fill that with a flexible airtight
00:33:32.140 --> 00:33:35.400
mastic seal all the way around both sides so
00:33:35.400 --> 00:33:40.339
in the lab tests we intent to eliminate that
00:33:40.339 --> 00:33:43.819
flanking around the sample or through the test
00:33:43.819 --> 00:33:47.640
apparatus so that the sample can perform at its
00:33:47.640 --> 00:33:49.720
best. But in the field, you want to consider
00:33:49.720 --> 00:33:53.440
that as well. And then finally, cavity absorption.
00:33:53.779 --> 00:33:55.940
We want to make sure that this is not a hollow
00:33:55.940 --> 00:33:59.920
cavity that will resonate. I have to be careful
00:33:59.920 --> 00:34:03.599
how I say this one, but the properties we talked
00:34:03.599 --> 00:34:06.039
about with sound absorbing materials apply in
00:34:06.039 --> 00:34:10.269
this cavity here. And you want to avoid materials
00:34:10.269 --> 00:34:17.409
that are very, very rigid to the point where
00:34:17.409 --> 00:34:20.389
they're increasing the stiffness of this wall
00:34:20.389 --> 00:34:24.690
and not adding much mass. So think about that.
00:34:24.750 --> 00:34:26.969
So materials that might be stiffening the wall
00:34:26.969 --> 00:34:31.010
and not adding much mass, those could actually
00:34:31.010 --> 00:34:36.289
hurt your STC rating. And then finally, damping.
00:34:36.880 --> 00:34:39.239
um there's a there's a way to introduce more
00:34:39.239 --> 00:34:41.719
friction in the vibration of these materials
00:34:41.719 --> 00:34:44.099
so this would be something like the viscoelastic
00:34:44.099 --> 00:34:47.519
damping compounds or the quiet gypsum board products
00:34:47.519 --> 00:34:50.460
that are out there these are real materials they
00:34:50.460 --> 00:34:53.179
have real benefits they're a good tool in the
00:34:53.179 --> 00:34:55.940
toolbox so i'll tell you a little bit about how
00:34:55.940 --> 00:35:00.639
we run this test we have a special set of chambers
00:35:00.639 --> 00:35:04.340
that's built where we have two reverberation
00:35:04.340 --> 00:35:08.519
chambers that are joined by an aperture in this
00:35:08.519 --> 00:35:11.239
case room one might serve as our source room
00:35:11.239 --> 00:35:16.960
so we're generating um about 110 decibels 120
00:35:16.960 --> 00:35:20.400
decibels of pink noise in that room i mean imagine
00:35:20.400 --> 00:35:23.239
that you're standing at the bottom of niagara
00:35:23.239 --> 00:35:26.840
falls inside of a cathedral that's what that's
00:35:26.840 --> 00:35:28.780
what it sounds like in that chamber you don't
00:35:28.780 --> 00:35:31.579
want to be in there and then we measure this
00:35:31.579 --> 00:35:34.699
average sound level spatial and time average
00:35:34.699 --> 00:35:37.800
in that chamber and then we make that another
00:35:37.800 --> 00:35:39.940
measurement on the other side of that chamber
00:35:39.940 --> 00:35:44.639
and then we correct for the area of the sample
00:35:44.639 --> 00:35:48.519
and the presence of sound absorption in the receive
00:35:48.519 --> 00:35:50.420
room there's also an ambient noise correction
00:35:50.420 --> 00:35:53.179
but that's in a lab condition that's almost negligible
00:35:53.179 --> 00:35:58.940
so that process tells us that all the sound that
00:35:58.940 --> 00:36:01.480
we're measuring in this receive room is coming
00:36:01.480 --> 00:36:05.760
through the sample because we've isolated all
00:36:05.760 --> 00:36:09.219
other paths that sound could take around it and
00:36:09.219 --> 00:36:17.940
the um yeah the the sound level oh that the reduction
00:36:18.699 --> 00:36:22.039
through that sample of that size is determined
00:36:22.039 --> 00:36:25.139
there using this equation here. So the transmission
00:36:25.139 --> 00:36:28.659
loss is the source level minus the receive level
00:36:28.659 --> 00:36:31.820
with that correction I mentioned before for area
00:36:31.820 --> 00:36:36.679
and sound absorption. All right. Finally, impact
00:36:36.679 --> 00:36:40.860
sound transmission. Now, I have to tell you,
00:36:40.900 --> 00:36:49.889
this is probably the most This topic is, I've
00:36:49.889 --> 00:36:53.670
seen more grown men crying in my life about anything,
00:36:53.869 --> 00:36:57.969
about this topic than about anything else. So
00:36:57.969 --> 00:37:02.710
imagine that you bought your dream condominium.
00:37:02.730 --> 00:37:07.630
You spent $2 million on this condominium and
00:37:07.630 --> 00:37:12.650
you move in and very quickly realize that you
00:37:12.650 --> 00:37:16.219
hear every single footstep. tap tap tap tap tap
00:37:16.219 --> 00:37:21.599
tap tap tap back and forth all day long in the
00:37:21.599 --> 00:37:23.940
in the ceiling above you hear every footstep
00:37:23.940 --> 00:37:28.079
from the person walking above you all day long
00:37:28.079 --> 00:37:31.500
now acoustic sometimes seems like it's not that
00:37:31.500 --> 00:37:34.519
big of a deal or you know less important than
00:37:34.519 --> 00:37:37.300
let's say having the right kitchen cabinets and
00:37:37.300 --> 00:37:41.159
countertop but when you have that situation and
00:37:41.159 --> 00:37:44.369
you're very noise sensitive you don't care what
00:37:44.369 --> 00:37:46.989
your countertops were made of. That is the number
00:37:46.989 --> 00:37:50.909
one problem in your entire life. And there are
00:37:50.909 --> 00:37:54.989
really no easy solutions here. So we encourage
00:37:54.989 --> 00:37:57.849
whenever possible that this consideration is
00:37:57.849 --> 00:38:01.809
made when a building is built and or when floor
00:38:01.809 --> 00:38:04.949
coverings are being installed so that you do
00:38:04.949 --> 00:38:08.199
it right the first time. how do we test this
00:38:08.199 --> 00:38:11.500
so in the very early days i think like 1950s
00:38:11.500 --> 00:38:15.659
let's say um they'll the method would be they
00:38:15.659 --> 00:38:18.619
would have a woman in high heel shoes walk in
00:38:18.619 --> 00:38:21.940
a figure eight pattern on the floor and make
00:38:21.940 --> 00:38:26.559
measurements below that and you know try to standardize
00:38:26.559 --> 00:38:29.159
the gates and the speed and all that stuff so
00:38:29.800 --> 00:38:32.320
This is problematic for a lot of reasons, right?
00:38:32.460 --> 00:38:35.440
So they came up with this machine. This is a
00:38:35.440 --> 00:38:40.000
standard tapping machine. And this is what we
00:38:40.000 --> 00:38:45.940
use in our IIC and field tests, our AIIC tests
00:38:45.940 --> 00:38:50.579
in the field. So E492 and E107. So this machine
00:38:50.579 --> 00:38:54.380
has a series of metal hammers, which are all
00:38:54.380 --> 00:38:58.550
dropped from a defined height. And this sequence
00:38:58.550 --> 00:39:03.650
happens at a defined speed. And it's basically
00:39:03.650 --> 00:39:07.750
like almost like an inline five engine. It's
00:39:07.750 --> 00:39:11.309
constantly tapping on the floor and it's loud,
00:39:11.590 --> 00:39:14.289
but it creates this kind of controlled standard
00:39:14.289 --> 00:39:17.949
impact noise function into the floor assembly.
00:39:18.710 --> 00:39:22.150
We'll take that machine and place it on the top
00:39:22.150 --> 00:39:26.300
of a floor ceiling assembly. And then. we make
00:39:26.300 --> 00:39:28.619
measurements in the room below so the source
00:39:28.619 --> 00:39:32.079
room and receive room is below there's also similar
00:39:32.079 --> 00:39:36.219
to e90 there's corrections for the sound absorption
00:39:36.219 --> 00:39:40.960
and ambient noise in the receive room so what
00:39:40.960 --> 00:39:43.619
are the properties of materials that will contribute
00:39:43.619 --> 00:39:47.539
to its impact sound isolation or its iic rating
00:39:47.539 --> 00:39:53.429
so maybe In my opinion, one of the most critical
00:39:53.429 --> 00:39:56.869
factors is that flexibility on the surface. So
00:39:56.869 --> 00:40:02.389
if you go back to the 70s and 80s in multifamily
00:40:02.389 --> 00:40:05.980
housing. you almost always had carpeted floors
00:40:05.980 --> 00:40:10.000
in an apartment. And this is why it was not as
00:40:10.000 --> 00:40:13.820
much of a hot topic back then, because that carpeting
00:40:13.820 --> 00:40:16.940
does a really good job of preventing the footfall
00:40:16.940 --> 00:40:20.980
noise from getting into the structure, into the
00:40:20.980 --> 00:40:28.019
subfloor structure. It eliminates that strike
00:40:28.019 --> 00:40:32.409
at the first. possible position so so that surface
00:40:32.409 --> 00:40:36.550
is very critical however we know that the modern
00:40:36.550 --> 00:40:40.510
homeowner modern consumer would rather saw off
00:40:40.510 --> 00:40:43.369
their own arm than have a carpeted living room
00:40:43.369 --> 00:40:48.440
right i get it so you the hard surface flooring
00:40:48.440 --> 00:40:51.820
options like tile and wood and laminate they
00:40:51.820 --> 00:40:54.739
just are inherently worse for iic performance
00:40:54.739 --> 00:40:57.059
and so you want to take special consideration
00:40:57.059 --> 00:41:03.099
on isolating these floors again generally it's
00:41:03.099 --> 00:41:05.820
better if you can get that isolation to happen
00:41:05.820 --> 00:41:09.769
further up in the in the structure so also mass
00:41:09.769 --> 00:41:13.309
is also critical and the presence of generally
00:41:13.309 --> 00:41:16.130
a suspended ceiling in general is also very important
00:41:16.130 --> 00:41:19.289
that's another trend you know as the demand for
00:41:19.289 --> 00:41:25.510
higher ceilings in condominiums is counter to
00:41:25.510 --> 00:41:31.730
the interest of the acoustics so exposed slab
00:41:31.730 --> 00:41:34.329
configurations where you look up from the room
00:41:34.329 --> 00:41:37.429
below and you see the actual concrete subfloor
00:41:37.429 --> 00:41:41.010
without anything suspended that's that's important
00:41:41.010 --> 00:41:43.449
to take consideration in acoustic performance
00:41:43.449 --> 00:41:48.050
as we mentioned before the iic rating and this
00:41:48.050 --> 00:41:51.909
is really critical to hammer in on iic performance
00:41:51.909 --> 00:41:57.030
iic is not a materials rating iic is not a rating
00:41:57.030 --> 00:42:00.980
on an underlayment or a floor covering IIC is
00:42:00.980 --> 00:42:04.980
a rating on the entire subfloor of which that
00:42:04.980 --> 00:42:07.559
floor covering or underlayment is one component.
00:42:08.340 --> 00:42:16.679
So you will sometimes see, maybe if you go into
00:42:16.679 --> 00:42:19.400
the big box store, you might see an underlayment
00:42:19.400 --> 00:42:23.539
with a label on it that says IIC 74, let's say.
00:42:23.639 --> 00:42:26.760
So the question one should ask is, well, okay,
00:42:26.860 --> 00:42:29.989
what was the assembly that was tested? is this
00:42:29.989 --> 00:42:33.210
iic 74 doesn't tell me anything in fact it's
00:42:33.210 --> 00:42:35.110
a clue that it was probably pretty substantial
00:42:35.110 --> 00:42:41.989
assembly so you'll want to look at the test laboratory
00:42:41.989 --> 00:42:44.989
test report which will give you a specifications
00:42:44.989 --> 00:42:48.210
for exactly what was tested including the finish
00:42:48.210 --> 00:42:52.369
floor underlayment subfloor suspended ceiling
00:42:52.369 --> 00:42:55.710
any isolators that were in place insulation in
00:42:55.710 --> 00:42:58.920
the cavity basically the whole build up this
00:42:58.920 --> 00:43:03.340
is very important so in like i said with with
00:43:03.340 --> 00:43:08.659
floor ceiling assemblies especially you you really
00:43:08.659 --> 00:43:12.619
want a lab test report to to verify um that before
00:43:12.619 --> 00:43:15.960
you you pay to have a flooring installed or you
00:43:15.960 --> 00:43:17.860
build a building that you know that you're going
00:43:17.860 --> 00:43:21.579
to have a satisfactory performance we do a lot
00:43:21.579 --> 00:43:23.500
of different tests on a lot of different floor
00:43:23.500 --> 00:43:28.840
finish floors underlayments suspended ceiling
00:43:28.840 --> 00:43:33.039
systems. The base slab by itself gets an STC
00:43:33.039 --> 00:43:37.940
56, which is good news, right? So that tells
00:43:37.940 --> 00:43:41.260
you, you pass the minimum building code. We'll
00:43:41.260 --> 00:43:43.719
get to that in a minute on what that is. But
00:43:43.719 --> 00:43:47.139
you pass that with just the slab. That's because
00:43:47.139 --> 00:43:50.440
even though the slab is very stiff, there is
00:43:50.440 --> 00:43:53.579
a lot of mass here. So, and that is really doing
00:43:53.579 --> 00:43:56.300
the work on the airborne sound transmission.
00:43:56.829 --> 00:44:01.889
um however even though you get stc for free um
00:44:01.889 --> 00:44:07.909
iic is a big consideration so without any consideration
00:44:07.909 --> 00:44:11.730
without any floor covering um you have iic of
00:44:11.730 --> 00:44:15.449
27. so if you had a polished concrete floor and
00:44:15.449 --> 00:44:19.710
an exposed slab on the room below that's a very
00:44:19.710 --> 00:44:25.269
poor iic performance 27. so What do you want
00:44:25.269 --> 00:44:29.010
to look for? Like I mentioned, you want to ask
00:44:29.010 --> 00:44:33.809
for an acoustical lab test report and lab test
00:44:33.809 --> 00:44:37.030
report. It's usually not a one page or two page
00:44:37.030 --> 00:44:40.909
document. It has a number of things. So I'll
00:44:40.909 --> 00:44:44.750
quickly go through what to look for in a lab
00:44:44.750 --> 00:44:47.469
test report. So obviously the testing agency
00:44:47.469 --> 00:44:52.269
who performed the test. How are they qualified
00:44:52.269 --> 00:44:55.289
to perform the test? So in our case, we're accredited
00:44:55.289 --> 00:44:57.730
by NAVLAB, which is the U .S. Federal Government's
00:44:57.730 --> 00:45:01.010
accreditation agency. There are other accreditations
00:45:01.010 --> 00:45:03.730
as well. But you want to make sure that this
00:45:03.730 --> 00:45:08.570
is a lab that's accredited to perform as a lab
00:45:08.570 --> 00:45:12.289
as well as to perform this test. We'll mention
00:45:12.289 --> 00:45:14.949
in this first paragraph here what the standards
00:45:14.949 --> 00:45:17.389
were that were followed to perform the test.
00:45:17.650 --> 00:45:20.070
We will tell you when the test was performed.
00:45:21.849 --> 00:45:25.570
the information provided by sponsor section.
00:45:25.809 --> 00:45:30.090
So starting with 2017, the 2017 version of ISO
00:45:30.090 --> 00:45:35.789
17025, they required labs to separate information
00:45:35.789 --> 00:45:38.679
that's provided by the sponsor. versus information
00:45:38.679 --> 00:45:40.940
that's directly observed by the lab which is
00:45:40.940 --> 00:45:44.400
really smart so we have a section for sponsor
00:45:44.400 --> 00:45:47.679
provided information as well as a section for
00:45:47.679 --> 00:45:52.460
our own observations and then most of our modern
00:45:52.460 --> 00:45:56.119
test reports starting around 2012 and later will
00:45:56.119 --> 00:45:59.239
have photos of the sample and and i don't know
00:45:59.239 --> 00:46:01.880
what you think about you but for me um it's a
00:46:01.880 --> 00:46:03.659
lot easier to figure out what's going on in a
00:46:03.659 --> 00:46:07.500
build by looking at photos than reading uh paragraph
00:46:07.500 --> 00:46:10.719
so we'll also provide one -third octave band
00:46:10.719 --> 00:46:12.940
results the single and the single number rating
00:46:12.940 --> 00:46:16.699
and you'll also have a certified signature on
00:46:16.699 --> 00:46:20.500
every report so once you authenticate this signature
00:46:20.500 --> 00:46:23.239
once i believe that anytime you see a future
00:46:23.239 --> 00:46:28.820
report from me identrust or will validate that
00:46:28.820 --> 00:46:35.550
signature when you open the pdf these the airborne
00:46:35.550 --> 00:46:39.650
and impact sound rating, STC and IIC, are referenced
00:46:39.650 --> 00:46:42.230
in the International Building Code for multifamily
00:46:42.230 --> 00:46:45.929
housing. So for airborne sound insulation, they
00:46:45.929 --> 00:46:51.309
want not less than STC 50, or if it's field tested,
00:46:51.590 --> 00:46:56.190
not less than NNIC 45, which is the field test,
00:46:56.329 --> 00:46:59.349
sort of not equivalent, but the field test version
00:46:59.349 --> 00:47:04.860
of E90, which is E336. now one might think well
00:47:04.860 --> 00:47:07.900
we should we should try to just do the field
00:47:07.900 --> 00:47:10.400
test because that's easier to pass than the lab
00:47:10.400 --> 00:47:15.179
test actually that's not not true oftentimes
00:47:15.179 --> 00:47:17.260
a field test can be more challenging because
00:47:17.260 --> 00:47:19.900
there's a lot of factors that could that you
00:47:19.900 --> 00:47:22.420
can't control that could be influencing the test
00:47:22.420 --> 00:47:25.699
results and we are seeing more and more where
00:47:25.699 --> 00:47:29.179
developers are being asked to provide both the
00:47:29.179 --> 00:47:32.039
lab tests prior to construction then the field
00:47:32.039 --> 00:47:37.519
test validation afterwards so um and then impact
00:47:37.519 --> 00:47:41.840
sound insulation iic 50 and similarly they allow
00:47:41.840 --> 00:47:45.519
five points flexibility for the nisr which is
00:47:45.519 --> 00:47:50.780
the field alternative so it should be noted that
00:47:50.780 --> 00:47:54.920
these ratings stc50 and iic50 even though this
00:47:54.920 --> 00:47:57.320
is the building code requirement this is really
00:47:57.320 --> 00:48:00.280
this should really be seen as a minimum acceptable
00:48:00.280 --> 00:48:03.460
performance for multi -family housing so this
00:48:03.460 --> 00:48:06.519
is not sound proof this is not high quality this
00:48:06.519 --> 00:48:11.460
is we we did the minimum and we got stc50 so
00:48:11.460 --> 00:48:15.900
luxury you know might be in the range of stc
00:48:15.900 --> 00:48:20.539
65 60 if you get your 60 65 if you can get it
00:48:20.539 --> 00:48:25.199
and then 55 to 60 might be a good reasonable
00:48:25.199 --> 00:48:28.280
target for you know high quality condominium
00:48:28.280 --> 00:48:31.579
so but there are a lot of different considerations
00:48:31.579 --> 00:48:35.570
there and a lot that goes into designing for
00:48:35.570 --> 00:48:38.429
that so in our experience most of the time when
00:48:38.429 --> 00:48:41.809
there are really significant complaints it's
00:48:41.809 --> 00:48:45.670
around this level or or slightly lower you know
00:48:45.670 --> 00:48:47.989
oftentimes the worst case scenario is someone
00:48:47.989 --> 00:48:52.269
you know does a field test and they get nnic
00:48:52.269 --> 00:48:55.449
45 and they're not happy with it but it passes
00:48:55.449 --> 00:49:00.329
the building code and that's that so just a consideration
00:49:00.329 --> 00:49:03.030
so anyone that's designing buildings to try to
00:49:03.030 --> 00:49:05.570
shoot for higher than these and where can you
00:49:05.570 --> 00:49:09.210
find information on on these test reports i'm
00:49:09.210 --> 00:49:10.929
going to share a couple examples for you that
00:49:10.929 --> 00:49:15.250
i really like um probably in my experience like
00:49:15.250 --> 00:49:18.269
one of the best comprehensive directories of
00:49:18.269 --> 00:49:21.690
wall assemblies and floors is this usg design
00:49:21.690 --> 00:49:25.309
studio they give fire ratings and stc ratings
00:49:25.309 --> 00:49:27.929
for all different types of assemblies and and
00:49:27.929 --> 00:49:31.219
i really like this um layout there's also the
00:49:31.219 --> 00:49:37.099
ga 600 which provides a big list of acoustical
00:49:37.099 --> 00:49:40.360
and fire performance for different systems and
00:49:40.360 --> 00:49:44.340
then product manufacturers will often make our
00:49:44.340 --> 00:49:47.820
test reports available on their website and you
00:49:47.820 --> 00:49:51.699
know if you see numbers and you're being held
00:49:51.699 --> 00:49:53.820
accountable for the acoustic performance of the
00:49:53.820 --> 00:49:56.239
building, I recommend reaching out to the technical
00:49:56.239 --> 00:49:59.539
support of the manufacturer and ask them for
00:49:59.539 --> 00:50:03.480
that test report. Clark Dietrich is another one.
00:50:03.539 --> 00:50:07.659
I really like the way they lay out their test
00:50:07.659 --> 00:50:10.219
results and for all their different products
00:50:10.219 --> 00:50:13.739
and systems. We also perform field testing as
00:50:13.739 --> 00:50:17.550
well. In the lab, we have perfect conditions
00:50:17.550 --> 00:50:20.650
we control for all variables and eliminate flanking
00:50:20.650 --> 00:50:24.309
paths but then field environments are often not
00:50:24.309 --> 00:50:28.050
ideal so when did you lab tests versus field
00:50:28.050 --> 00:50:31.329
so lab tests are performed on products and systems
00:50:31.329 --> 00:50:36.469
before the sale and installation and field tests
00:50:36.469 --> 00:50:39.730
are performed on building systems after the building
00:50:39.730 --> 00:50:42.969
is is built so one thing to remember whenever
00:50:42.969 --> 00:50:47.710
you hear these ratings stc nrc iic these are
00:50:47.710 --> 00:50:51.289
all lab test results so these are not field tests
00:50:51.289 --> 00:50:54.909
there are field tests that are similar but they
00:50:54.909 --> 00:50:58.269
have different classifications so an acoustic
00:50:58.269 --> 00:51:02.130
requirement for stc rating is asking you for
00:51:02.130 --> 00:51:06.300
a lab test And that typically is sponsored by
00:51:06.300 --> 00:51:08.960
the product manufacturer, although we're seeing
00:51:08.960 --> 00:51:12.460
more and more mock -ups for a specific building,
00:51:12.719 --> 00:51:16.000
project -specific mock -ups. When you're involved
00:51:16.000 --> 00:51:19.039
in the construction of a building, the acoustical
00:51:19.039 --> 00:51:21.039
considerations are very important. And we talked
00:51:21.039 --> 00:51:25.699
about where things can go sideways and all that
00:51:25.699 --> 00:51:28.159
complexity, and then balancing that out with
00:51:28.159 --> 00:51:31.500
the structural and fire requirements, which...
00:51:31.929 --> 00:51:34.190
even us acquisitions will say yeah yeah fire
00:51:34.190 --> 00:51:37.630
is uh directly a life safety issue you should
00:51:37.630 --> 00:51:40.530
not compromise your fire performance so that's
00:51:40.530 --> 00:51:42.530
one of the things that an acoustical consultant
00:51:42.530 --> 00:51:46.349
will do on your project is is help to work with
00:51:46.349 --> 00:51:49.050
those various trades to ensure a good outcome
00:51:49.050 --> 00:51:52.050
so there's a trade organization for acoustical
00:51:52.050 --> 00:51:56.170
consultants the ncac and they have a directory
00:51:56.170 --> 00:51:59.750
and you can most likely find someone in your
00:51:59.750 --> 00:52:03.050
area that's qualified to consult on the project.
00:52:03.829 --> 00:52:08.429
Another credential that I think this might be
00:52:08.429 --> 00:52:12.429
the most well -respected credential in the trade
00:52:12.429 --> 00:52:14.590
of acoustical consultants or acoustical engineering,
00:52:14.829 --> 00:52:20.550
this would be the INCE board certification. And
00:52:20.550 --> 00:52:24.750
there's a directory on INCE USA website. um which
00:52:24.750 --> 00:52:27.510
can find board certified engineers in your directory
00:52:27.510 --> 00:52:30.809
when you're dealing with really technical noise
00:52:30.809 --> 00:52:35.809
control engineering i definitely recommend taking
00:52:35.809 --> 00:52:39.050
a look at this directory and finally in review
00:52:39.050 --> 00:52:45.869
um sound absorption is classified by the noise
00:52:45.869 --> 00:52:49.329
reduction coefficient or nrc rating this is nrc
00:52:49.329 --> 00:52:52.530
is specifically related to the behavior of sound
00:52:52.530 --> 00:52:56.050
within a space echo and reverberation sound reflections
00:52:56.050 --> 00:53:00.369
sound transmission class stc this is specifically
00:53:00.369 --> 00:53:03.869
related to airborne sound transmission through
00:53:03.869 --> 00:53:08.409
a wall and then impact insulation class this
00:53:08.409 --> 00:53:12.030
is related to the footfall noise that you hear
00:53:12.030 --> 00:53:15.960
in the floor ceiling assembly above you Thank
00:53:15.960 --> 00:53:17.840
you for listening to today's episode and please
00:53:17.840 --> 00:53:19.880
be sure to subscribe to Catalyst Conversations.
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To learn more and secure your spot, visit catalystacoustics
00:53:33.559 --> 00:53:36.320
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00:53:36.320 --> 00:53:38.300
and stay tuned for more episodes as we continue
00:53:38.300 --> 00:53:40.619
to explore noise and sound control advancements
00:53:40.619 --> 00:53:42.739
shaping the future of industries worldwide.