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

2. Fundamentals of Architectural Acoustics

3. 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. *

4. 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

5. Acoustics

6. 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.

7. 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.

8. 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

9. 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.

10. Acoustics
Noise pollution is huge especially in our cities

11. Acoustics

12. Acoustics
Inverse Square Law
Not in textbook

13. Sound in Enclosed Spaces
Acoustics
Chapter 18
Sound in Enclosed Spaces

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

15. Acoustics

16. Acoustics
STC

17. Acoustics
NRC

18. Acoustics

19. Acoustics

20. Acoustics

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

22. 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

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

24. 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

25. 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

26. 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.

27. 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

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

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

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

31. 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

32. I can explain everything

33. 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

34. 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

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

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

37. 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

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

39. 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

40. 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

41. Sound Absorption
3.32 seconds vs seconds

42. What! vs seconds

43. Is this a big enough difference?

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

45. 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

46. WHAT!
Sound Absorption
Is this enough?

47. Let’s look at a rule of thumb.

48. 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

49. $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)

50. Doesn’t make a lot of sense

51. Think about it!?

52. encore

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

54. 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

55. 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

56. 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.

57. Sound Absorption
YEAH!

58. Acoustics

61. Acoustics

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

63. 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 ……..

64. Acoustics
Bathrooms!

65. Acoustics
Lets start with the floor.

66. Acoustics

67. Acoustics

68. Acoustics

69. Acoustics
Now the walls

70. Acoustics

71. Acoustics

72. Acoustics

73. Acoustics

74. Acoustics

75. Acoustics

76. 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.

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

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

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

80. 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.

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

82. 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

83. Acoustics

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

85. Acoustics
Other Stuff

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

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

88. 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.

89. 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.

90. Acoustics
Always run gypsum bd. behind soffits.

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

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

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

94. Acoustics
What about fine tuning for Commercial Buildings

95. 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!!!! "

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

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

98. Acoustics

99. Acoustics

100. Thank you for being a great class