Acoustics OR HOW TO MAKE A CLIENT HAPPY

Acoustics OR HOW TO MAKE A CLIENT HAPPY

ACOUSTICS 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 Frequency -20 Hz - Ultrasound 20, 000 Hz 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 d. B. 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 15 d. B sound is ten times louder than a 14 d. B sound. * Lesson 49: Properties of Sound by Mr. Clintberg’s Study Physics

ACOUSTICS One of the loudest manmade sounds 215 d. B 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 d. B.

ACOUSTICS Noise pollution is huge especially in our cities

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ACOUSTICS Inverse Not Square Law in textbook

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 CSI Specification Division 09511 – Acoustical Panel Ceilings See Handout in class Also available on line at Arch 433 - Web Site

ACOUSTICS Review CSI Specification Division 09511 – Acoustical Panel Ceilings Submittals Ceiling Samples – tile and grid Tile 6 inch square samples Grid boxes – 3 samples each Follow directions in section 01330 – Submittal Procedures Ceiling layout – drawings – 3 sets Attachment methods

ACOUSTICS Review Specification CSI Division 09511 – Acoustical Panel Ceilings Quality Assurance Class “A” Coordination – Anything above the ceiling Extra Material

ACOUSTICS Review Specification CSI Division 09511 – 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 CSI Division 09511 – 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 09511 – 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 09511 – Acoustical Panel Ceilings Acoustical Sealant At perimeter joints and openings Flame spread & smoke development < 25 per ASTM E 84 Exposed At perimeter joints and openings Flame spread & smoke development < 25 per ASTM E 84 Concealed BA-98 Pecora or Tremco Act. Sealant AC-20 FTR or Sheetrock Act. Sealant, USG

ACOUSTICS Review Specification CSI Division 09511 – Acoustical Panel Ceilings Execution Balance boarders Splay hangers Sealant @ wall angle Screw attach wall angle Cleaning

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

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

SOUND ABSORPTION The Formula T =. 05 V/a and NR = 10 log (a 2/a 1) 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’= 320 sf Front 14’x 32’= 448 sf Sides (12’ave. x 98’) x 2 = 2, 352 sf 3, 120 sf x ά . 02 = 62. 4 Floor 31 x 98 3, 038 sf x ά. 10 = 303. 8 31 x 98 3, 038 sf x ά. 06 = 182. 3 Ceiling Total 548. 5

SOUND ABSORPTION Wallace Clement Sabine Father of Architectural Acoustics T =. 05 V/a

SOUND ABSORPTION The Formula T =. 05 V/a T = Time of Reverberation V = Volume a = Sabins

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

SOUND ABSORPTION With acoustical tile & carpet, what would be the reverberation time?

SOUND ABSORPTION Walls Back Front Sides 10’x 32’= 320 14’x 32’= 448 (12’ave. x 98’) x 2 =2, 352 Floor with Carpet Ceiling Sabins ά 3, 120 sf x ά. 02 = 31 x 98 3, 038 sf x ά. 14 = 62. 4 425. 32 - Acoustical tile (5 x 7) 8 each 280 sf x ά. 85 = 238 3, 038 sf – 280 sf 2, 758 sf x ά. 06 = 165. 5 w/o carpet (769. 7) Total 891. 22

SOUND ABSORPTION The Formula T =. 05 V/a V = Volume of room 31’x 98’x 12 a = sabins of 891. 22 T=. 05(31’x 98’x 12’)/ 891. 225 T=. 05(36, 456)/ 891. 22 T= 2. 04 seconds

SOUND ABSORPTION 3. 32 seconds vs. 2. 04 seconds

What! 2. 04 vs. 3. 32 seconds

Is this a big enough difference?

SOUND ABSORPTION NR = 10 log (a 2/a 1) NR = Noise reduction a 2 = 2. 04 seconds a 1 = 3. 32 seconds

SOUND ABSORPTION NR = 10 log (a 2/a 1) 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

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 for an imperceptible noise reduction! (For 1. 48 db reduction just for the acoustical tile)

Doesn’t make a lot of sense

THINK ABOUT IT!?

ENCORE

SOUND ABSORPTION Seating 110 seats Fabric Seats = ά. 56 Audience = ά. 80

SOUND ABSORPTION Floor 3, 038 sf x ά . 10 = Floor area (5 x 98)x 2 = 980 sf (32 -10) x 8 = 176 sf (32– 10) x 5 = 11 o sf 1, 266 sf 3, 038 sf – 1, 266 sf = 1, 776 sf seating area 303. 8

SOUND ABSORPTION Walls With students = 47. 04 1, 266 sf x ά. 14 = 177. 24 1, 776 sf x ά. 80 Floor with Carpet 3, 120 sf x ά. 02 =1, 402. 8 Ceiling - Acoustical tile (5 x 7) 8 each 280 sf x ά. 85 = 238 3, 038 sf – 280 sf 2 758 sf x ά. 06 = 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!

ACOUSTICS Lets start with the floor.

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ACOUSTICS Now the walls

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ACOUSTICS A standard wall 2 x 4 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 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 Sound deadening board both sides STC 54 w/ insulation and sound deadening board both sides STC 57

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ARCH 433 Mid Term Exam March 6 th 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.

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

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

ACOUSTICS What about fine tuning for Commercial Buildings

ACOUSTICS "Come out to the coast, we'll get together, have a few laughs. . . 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