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Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

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Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015
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Page 1: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Applications of Architectural AcousticsTufts University – ME 93September 10, 2015

Page 2: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Outline• Sound Proofing vs. Acoustical Treatment• Concerns addressed through acoustical treatment• Materials used in acoustical treatment• Measurement tools in acoustic analysis• Considerations in small recording spaces• Next steps

Page 3: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Sound ProofingReducing sound transmission between spaces

Source: Dan Russell, Penn State Mass = A+ sound proofingAir Between Two Decoupled Walls = B sound proofing

Page 4: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Sound ProofingAchieved with:• Mass, Isolated Construction and Tight Closures• Cinder blocks for speaker stands, heavy doors• Room-within-a-room construction• Door, window and wall seals

• See White: Chapter 18 for more information

Page 5: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Acoustical TreatmentDesigned for correction

Page 6: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Acoustical TreatmentDesigned for a particular purpose and character

Page 7: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Acoustical TreatmentDesigned for recording instruments & ensembles

Page 8: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Acoustical TreatmentDesigned for critical listening and assessment

Page 9: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Reflections• Any hard surface will likely reflect sound• Any hard flat surface that is larger than the

wavelength of a particular frequency will likely reflect energy at that frequency and above

Frequency1 kHz

Wavelength1 foot

Period1 ms

λ= Vf

Page 10: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Reflections• Echoes are distinct reflections where we can pick

out the individual occurrences.• We start hearing distinct delays around 20 ms

• Reflections of less than 20 ms can result in comb filtering

Comb filter caused by two signals generated1 ms apart

Page 11: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Frequency Specific IssuesModes or Standing Waves• Can be calculated

and mitigated

• Types of room modes:• Axial = 2 surfaces• Tangential = 3 surfaces• Oblique = 4 or more surfaces

Page 12: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Calculating Axial Modes

f = n(c / 2D)

Frequency of the mode

Dimension between the

two boundary surfaces

Speed of Sound(1130 ft/second)

Positive Integer

LENGTH WIDTH HEIGHT

1st Mode

2nd Mode

3rd Mode

4th Mode

Page 13: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Frequency Specific IssuesNodes• Hard to prevent; move your groove thing

Page 14: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Treatment Materials• Absorbers• Diffusors• Reflectors

Page 15: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Absorbers• Convert acoustical energy into heat• The amount of heat generated is marginal

• Common absorbers• Foam• Carpet• Draperies• Soft furniture• Large Mammals

Page 16: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Absorption Coefficients

• Measured across the spectrum• 0 = perfect reflector 1 = perfect absorber• Noise Reduction Coefficient = average of four octaves

(250, 500, 1k, 2k)• We generally want to absorb equally across the spectrum• White pg. 169 has coefficients for common materials

Page 17: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Decay time

Page 18: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Calculating decay time

0.049Vf

SA

0.161Vm

SA

RT60 =

RT60 =

Sabine’s Equation:V = volume of the space

(in cubic feet or meters)

S = absorbing surface area

(in ft2or m2)

A = absorption coefficient(in Sabins)

Page 19: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Measuring decay time

Page 20: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Anechoic SpacesUsed for measurement

Page 21: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

DiffusorsBlackbird Studio,Nashville

Page 22: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Diffusors Quadratic Fractal

Frequency and scatter patterns depend on size/shape

Page 23: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Reflectors• Parallel Walls• Offset/non-parallel designed walls to redirect

sound• Domes & curves

Page 24: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Intentional ReflectorsAcoustic shells

Kennedy Center – before & after acoustic shell

Page 25: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Measurement tools• EASE• SMAART• REW • Faber Acoustical

Page 26: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Building a small studio

Page 27: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Speaker placement

6 ft.

6 ft.

6 ft.

Use heavy cinder block speaker stands to decouple from the floor

Page 28: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Mix Position

6 ft.

6 ft.

6 ft.

Page 29: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Major reflection issues

6 ft.

6 ft.

6 ft.

BOOKS

BOOKS

RA

CK

OF

CLO

TH

ES

Grow more hair

Beware of desk reflections

Page 30: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Isolation & sound proofingWhat sounds don’t we want in the recording space?

What sounds don’t we want in the control room?

Page 31: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Recording Acoustic Instruments• Special Concerns• Sound proofing• Room volume

• Does the sound have time to develop?

• Ambient noise floor• HVAC• Computers and noisy devices

• Sonic character

Page 32: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Safety and Aesthetics• Fireproofing is a thing• Aesthetics are also a thing• If it sounds good, is it good?

Page 33: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Work with what you have• Check low-end in good quality headphones• Look for drastic gestures in your work• Just do something and learn

Page 34: Applications of Architectural Acoustics Tufts University – ME 93 September 10, 2015.

Next Steps• Fields of acoustics• Architectural Acoustics Graduate Programs• Internships related to Architectural and Musical

Acoustics• Job descriptions for careers related to Acoustics• Play with free toys, check out additional resources• What can you do to optimize your own space?


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