Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Term 2 Theory Prep > Acoustics > Flashcards

Acoustics Flashcards

1
Q

The Boston symphony hall was acoustically designed by _______

A

Wallace Sabine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

DEF: antinode

A

the point where the amplitude of a standing wave is at is maximum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

DEF: node

A

point of no vibration, essentially the zero crossing of a waveform

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

DEF: mode

A

a room resonance, a standing wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

DEF: axial modes

A

a resonance between two room parallel surfaces (one pair)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

DEF: tangential modes

A

a resonance between four room surfaces (two pairs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

DEF: oblique modes

A

a resonance between all six room surfaces (3 pairs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

The Schroeder Frequency of a room determines:

A

the point at which resonances become less problematic reflections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Reduction of reflections to an imperceptible loudness is called:

A

RT60

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

DEF: RT60

A

The time requird for the sound in an enclosure to decay 60 dB from an initial steady-state level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

An absorption coefficient of 0 equals:

A

total reflection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

In order to take an impuse response a room may be excited by ________

A

a sine sweep or a loud click (ie. gunshot)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

In order to catch a wavefront at maximum velocity an absorber must be equal to what fraction of a wavelength?

A

1/4 wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does an air cavity between an absorber and a boundary affect its acoustic performance?

A

It increased the performance at lower frequencies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe a Tom Hidley control room design

A

a reflective front wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

In a control room do you want parallel or non-parallel surfaces?

A

Non parallel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the Sabine Equation?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do we use Sabine’s equation to calculate?

A

reverb time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Identify the type of control room design

A

a Tom Hidley design

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does thickness of a material affect it’s absorption coefficient at lower frequencies?

A

thicker abosrbes more of lower frequencies as they have larger physical soundwaves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

DEF:

absorption

A

When sound energy is converted into heat energy as it passes through a medium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

how can you increase diffusion?

A
  • non parallel surfaces
  • use of geometric irregularities
  • use of concave surfaces or diffusion panels
  • use of every day objects (ie. book cases)
23
Q

name this diffuser

A

MLS ( Maximum length sequence) Diffuser

24
Q

DEF:

room mode

A

the normal modes of vibration in an enclosed space

25
Q

name this diffuser

A

skyline diffuser

26
Q

name this diffuser

A

QRD (Quadratic Residue Diffuser)

27
Q

name this diffusor

A

Schroeder’s Diffusor

28
Q

What constitutes a perfectly diffuser environment?

A
  • no measured frequency or level irregulariries
  • smooth reverberation decay
  • same rever decay for all frequencies and from all directions
  • same reverb time at all points in the room
29
Q

name this acoustic treatment

A

bass trap

30
Q

name this acoustic treatment

A

perforated panel absorbers

31
Q

name this acoustic treatment

A

Helmholtz Resonator

32
Q

name this acoustic treatment

A

Helmholtz Resonator

33
Q

What equation is used to calculate the maximum frequency that can be absorbed by a substance?

A
34
Q

with porous absorbers, what dictates the degree of absorption?

A

the space between the fibres

if fibres are not packed closely enough, little energy will be lost as heat

if fibres are packed too closely, sound may not penetrate absorber sufficiently

35
Q

name this acoustic treatment

A

porous absorbers

36
Q

DEF:

acoustic absorption

A

the process by which a medium takes in sound energy as opposed to reflecting it. Part of the absorbed energy is transformed into heat and part is transmitted through the absorbing body

37
Q

What word do we use to discribe the sound energy that has been converted to heat via acoustic absorption

A

energy transformed into heat is said to have been ‘lost’

38
Q

Who developed the quadratic residue diffuer (QRD)?

A

Manfred R. Schroeder

39
Q

In a QRD the well depth dictates _______

A

the lowest frequency for diffusion

40
Q

In a QRD the well width dictates the ________

A

highest frequency for diffusion

41
Q

what equation is used to calculate the well depth sequence in a QRD?

A
42
Q

what does the ‘modulo’ refer to?

A

the remainder

43
Q

What is the use of a Helmholtz resonator?

A

used to achieve absorption at lower frequencies

44
Q

DEF:

STC

A

Sound Transmission Class

a single number used to describe a series of transmission loss measurements made at frequency intervals throughout the frequency range. A standardised class system based on how well a medium attenuates sound.

45
Q

what does MLS stand for?

A

Maximum length sequence

46
Q

What are the three godlen room ratios?

A
47
Q

What equation is used to calculate a room mode?

A
48
Q

What equation is used to calculate the Schroeder frequency?

A
49
Q

What equation do you use to calculate standing waves?

A
50
Q

DEF:

standing wave

A

a resonance condition in an enclosed space in which sound waves travelling in one direction interact with those travelling in the opposite direction , resulting in a stable condition

51
Q

DEF:

reflection

A

sound is reflected much like light, with the angle of incidence equaling the angle of reflection

52
Q

DEF:

Helmholtz resonator

A

a reactive, tuned sound absorber

53
Q
A

Term 2 Theory Prep (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions