# Or How to make a client happy

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Or How to make a client happy
Acoustics Or How to make a client happy

Fundamentals of Architectural Acoustics

Acoustics Sound is a longitudinal wave.
Remember that longitudinal waves are made up of areas where the wave is compressed together, and other areas where it is expanded. Sound can be vibration which is pressure – felt but not heard. We will look in detail at three fundamental characteristics of sound: Speed, Frequency, and Loudness. *

Acoustics Speed The speed of sound in air actually depends on the temperature of the air. The sound travels faster through media with higher elasticity and/or lower density. Speed of sound is 1130 feet per second or 344 m/s Light is 186,000 miles per second

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Acoustics Frequency Most often we will be looking at sound waves that humans can actually hear, which are frequencies from 20 – 20,000 Hz. Infrasonics -20 Hz - Ultrasound 20,000Hz Frequency is sometimes referred to as pitch.

Acoustics Loudness The loudness of a sound depends on the wave’s amplitude. This is why a stereo system has an “amplifier”, a device that increases the amplitude of sound waves. The louder a sound, the bigger the amplitude. This is also a way of measuring the amount of energy the wave has.

Acoustics Loudness The system used to measure the loudness of sounds is the decibel system, given the unit dB. The decibel system is based on logarithms, which means for every step up by one, the sound is actually ten times louder. For example, a 15dB sound is ten times louder than a 14dB sound. * Lesson 49: Properties of Sound by Mr. Clintberg’s Study Physics

Acoustics One of the loudest man-made sounds 215 dB
That much sound energy creates heat. Water is used to absorb the energy That’s steam you see. It’s not all smoke. If they did not use water to absorb the sound, the shuttle and tower would fail due to the energy generated from 215 dB.

Acoustics Noise pollution is huge especially in our cities

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Acoustics Inverse Square Law Not in textbook

Sound in Enclosed Spaces
Acoustics Chapter 18 Sound in Enclosed Spaces

Acoustics Sound Absorption Noise Reduction Coefficient (NRC)
Verses Sound Transmission Coefficient (STC) (textbook class it Sound Transmission Class)

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Acoustics STC

Acoustics NRC

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Acoustics Review Specification
CSI Division – Acoustical Panel Ceilings See Handout in class Also available on line at Arch Web Site

Acoustics Review Specification
CSI Division – Acoustical Panel Ceilings Submittals Ceiling Samples – tile and grid Tile 6 inch square samples Grid boxes – 3 samples each Follow directions in section – Submittal Procedures Ceiling layout – drawings – 3 sets Attachment methods

Acoustics Review Specification
CSI Division – Acoustical Panel Ceilings Quality Assurance Class “A” Coordination – Anything above the ceiling Extra Material

Acoustics Review Specification
CSI Division – Acoustical Panel Ceilings Manufactures - Panels Mineral Base Type III (see slide 24) Pattern EI (see your handout for “E”+ “I” STC -35 Tegular Edge Size 24”x 24” Manufacture – Armstrong – Cirrus 584 (or equal) “by” Celotex or USG

Acoustics Review Specification There are 20 types A Type III
CSI Division – Acoustical Panel Ceilings Types of Material There are 20 types A Type III Mineral base with painted finish; Type includes: Form 1 Nodulated, cast, or molded Form 2 Water felted Form 3 Dry felted

Acoustics Review Specification
CSI Division – Acoustical Panel Ceilings Manufactures – Grid Direct Hung Powdered-Actuated Fasteners in Concrete - OK Wire – 12 gauge Hold Down Clips – Yes Grid – 15/16” Manufactures – Armstrong, Chicago, Interiors Inc.

Acoustics Review Specification
CSI Division – Acoustical Panel Ceilings Acoustical Sealant At perimeter joints and openings Flame spread & smoke development < 25 per ASTM E84 Exposed Concealed BA-98 Pecora or Tremco Act. Sealant AC-20 FTR or Sheetrock Act. Sealant, USG

Acoustics Review Specification
CSI Division – Acoustical Panel Ceilings Execution Balance boarders Splay hangers wall angle Screw attach wall angle Cleaning

Acoustics Let’s do a sound absorption problem!!!!

Carpenter Hall Room 102 Sound Absorption
Foot print of Carpenter Room 102 32’ x 98’ Ceiling Ht. 14’ to 10’ average 12’ Sound 500Hz

We’ll get to the formulas later
Sound Absorption The Formula T = .05 V/a and NR = 10log (a2/a1) We’ll get to the formulas later

I can explain everything

Sound Absorption Walls Plaster, gypsum or lime on brick = ά .02 Floor
Wood = ά .10 Ceiling Plaster, gypsum or lime = ά .06 (See handout) ά = Noise Reduction Coefficient (NRC) or Sound Absorption Coefficient This is similar to the example on page 791

Sound Absorption What is the reverberation time with no finishes?
Walls ά Sabins Back 10’x 32’= sf Front ’x 32’= sf Sides (12’ave. x 98’) x 2 = ,352 sf 3,120 sf x ά .02 = Floor 31 x ,038 sf x ά = Ceiling 31 x ,038 sf x ά = Total

Father of Architectural Acoustics
Sound Absorption T = .05 V/a Wallace Clement Sabine Father of Architectural Acoustics

The Formula T = .05 V/a Sound Absorption T = Time of Reverberation
T = Time of Reverberation V = Volume a = Sabins

T= 3.32 seconds Sound Absorption The Formula T = .05 V/a
V = Volume of room 31’x 98’x 12 a = sabins of = 548.5 T= .05(31’x 98’x 12’)/ 548.5 T= .05(36,456)/548.5 T= 3.32 seconds

With acoustical tile & carpet, what would be the reverberation time?
Sound Absorption With acoustical tile & carpet, what would be the reverberation time?

Sound Absorption Walls ά Sabins Floor with Carpet Ceiling
Back 10’x 32’= Front 14’x 32’= Sides (12’ave. x 98’) x 2 = 2,352 3,120 sf x ά = Floor with Carpet 31 x 98 3,038 sf x ά = Ceiling - Acoustical tile (5x7) 8 each sf x ά .85 = 238 3,038 sf – 280 sf 2,758 sf x ά = 165.5 w/o carpet (769.7) Total

T= 2.04 seconds Sound Absorption The Formula T = .05 V/a
V = Volume of room 31’x 98’x 12 a = sabins of T= .05(31’x 98’x 12’)/ T= .05(36,456)/ T= 2.04 seconds

Sound Absorption 3.32 seconds vs seconds

What! vs seconds

Is this a big enough difference?

Sound Absorption NR = 10log (a2/a1) NR = Noise reduction a2 = 2.04 seconds a1 = 3.32 seconds

Acoustical tile alone = 1.48 db
Sound Absorption NR = 10log (a2/a1) NR = 10 log (2.04 / 3.32) NR = 10 log (.614) NR = 2.11 Noise Reduction of = 2.11 db Acoustical tile alone = 1.48 db

WHAT! Sound Absorption Is this enough?

Let’s look at a rule of thumb.

Sound Absorption Change in Intensity Level, db 1 3 5 10 18
Change in Apparent Loudness Almost imperceptible Just perceptible Clearly noticeable Twice as loud Very much louder

\$8,296.00 for an imperceptible noise reduction!
Sound Absorption For a noise reduction of 2.11! Carpet 3,136 sf of carpet or 348 sy at \$22.00 sy = \$7,666.00 Acoustical Ceiling Tile 280 sf x \$2.25 = \$630.00 Total cost furnished and installed \$8,296.00 \$8, for an imperceptible noise reduction! (For 1.48 db reduction just for the acoustical tile)

Doesn’t make a lot of sense

encore

Sound Absorption Seating 110 seats Fabric Seats = ά .56
Audience = ά .80

Floor Sound Absorption Floor area (5 x 98)x 2 = 980 sf
3,038 sf x ά = Floor area (5 x 98)x 2 = 980 sf (32 -10) x 8 = 176 sf (32–10) x 5 = 11o sf 1, 266 sf 3,038 sf – 1,266 sf = 1,776 sf seating area

Sound Absorption 1,776 sf x ά .80 =1,402.8
Walls ,120 sf x ά = Floor with Carpet 1,266 sf x ά = With students 1,776 sf x ά =1,402.8 Ceiling - Acoustical tile (5x7) 8 each sf x ά .85 = 238 3,038 sf – 280 sf sf x ά = 165.5 Total 2,030.58

Sound Absorption T= .05(36,456)/ 2,030.58 T= .90 seconds The seating alone with or without students has much more value than either the ACT or the Carpet.

Sound Absorption YEAH!

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Acoustics How to reduce the noise sooooo…..
Let’s cut to the chase. We’ll use a bathroom wall to begin with.

Acoustics The goal is to design and construct walls, ceilings and floors that reduce or eliminate unwanted noise or sound. Sound that we find in ……..

Acoustics Bathrooms!

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Acoustics Now the walls

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Acoustics A standard wall 2x4 studs and plates with ½” gypsum board on both sides has a STC of 32 to 36. Add insulation STC 35 to 39.

Acoustics Metal Studs STC 37 to 41 w/ insulation STC 44 to 48

Acoustics Wood Stager Studs Common plate STC 46 to 48
Without insulation STC 38 to 42

Acoustics Wood Stager Studs Common plate w/ insulation STC 46 to 50
Without sound bd. and insulation STC 38 to 42

Acoustics Make sure the joist are parallel to wall and
Dual plates and studs STC 42 to 44 W/ insulation STC 50 to 53 Make sure the joist are parallel to wall and all flooring and ceiling material divided.

Acoustics Stud wall 2 x 4 with resilient channel and insulation
STC 40 to 42 w/ insulation STC 47 to 51

Acoustics Metal studs w/ sound deadening board one side STC 52
both sides STC 54 w/ insulation and sound deadening board both sides STC 57

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Arch 433 Mid Term Exam March 6th What does it cover ?

Acoustics Other Stuff

Acoustics Other than walls, ceilings and floors , how can we
design and build spaces to reduce unwanted sound.

Acoustics Because Mom and Dad do not want to
wake-up baby……when …well .. you…..know!

Acoustics In rooms where you do not want sound to travel through HVAC ductwork, install separate supply and return systems. Air ducts are great for carrying sound.

Acoustics Always have gypsum bd. cut tight and sealed around
Receptacle boxes. Use sound deadening products behind the boxes. Never place boxes back to back or in the same stud cavity.

Acoustics Always run gypsum bd. behind soffits.

Acoustics If you are creeping home late, never nail the stair
stringers to wall studs.

Cast Iron Plastic Pipe Acoustics Verses
Nothing worst than hearing someone flush the toilet or wash their hands.

Acoustics The use of neoprene gaskets and hubless coupling with cast iron pipe and fittings significantly reduces noise and vibration.. Cast Iron

Acoustics What about fine tuning for Commercial Buildings

Acoustics "Come out to the coast, we'll get together, have a few laughs... Hold it… Hold it…. Max said this ductwork wouldn’t hold me up!!!! "

Acoustics I call this the Die Hard Ceiling System Lecture
Let me show you a much better system- See lecture i.e. white board

Acoustics Let me show you a much better system-
See lecture i.e. white board

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Thank you for being a great class