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Acou
Acoustics and psyc
98
Music
Undergraduate 2
04/28/2013

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Cards

Term
HVAC:| what does it stand for and what are the 3 things it causes?
Definition
Heating, Ventilation, Air conditioning.

Noise, flanking(noise brought in from another room through the ac vents), wind.
Term
definition: Gobo
Definition
Used in the studio to isolate one sound source from another. Only effective at blocking frquencies whose WL's are smaller than the dimensions of the gobo
Term
6 foot gobo, what freqs can it block?
Definition
1130/6 = 188
Term
definition: diffraction
Why does it happen?
Definition
the bending of a sound wave around an obstacle or object. This happens whenever the WL of a signal is greater than the dimensions of the obstacle.
Term
Lower Frequency means longer or shorter WL?
Definition
Longer
Term
Mass Law: 2 times the mass equals
___db increase in isolation
Definition
6db. Increases isolation
Term
Mass Law: half the mass equals
___db decrease in isolation
Definition
6db. decreases isolation
Term
What does TL stand for? And what is it?
Definition
Transmission Loss. A specific ratio in db between energy that goes in and goes out. The higher the TL, the better the isolation.
Term
TL of 500hz 36 db. Sound going in is 100 db. How loud is the sound coming out?
Definition
65 db
Term
2x freq = ___db change in TL
Definition
+6 db
Term
1/2 freq = ___ db change in TL
Definition
-6 db
Term
2x mass = ___db change in tl
Definition
+6 db
Term
What does STC stand for and what is it?
Definition
Sound Transmission Class. A single number rating covering the TL performance of a construction between 125hz and 4khz.
Term
Is STC a ratio or a single number?
Definition
Single number
Term
Frequencies between 125hz and 4khz at a level of 97 db going through a material with a STC of 27 will be how loud coming out?
Definition
70 db
Term
What does NRC stand for and what is it?
Definition
Noise Reduction Coefficient. An average rating of noise reduction. Average of 250hz,500hz,1khz,2khz. Is a number between 0-1.
Term
NRC is an average rating through what freqs?
Definition
250hz, 500hz, 1khz, 2khz
Term
Is NRC specific or broad?
Definition
Broad
Term
Is TL specific or broad?
Definition
specific
Term
Is A.C. specific or broad?
Definition
specific
Term
Do TL and STC say anything about low frequencies?
Definition
Nope
Term
What does AC stand for and what is it?
Definition
Absorption Coefficient. A specific rating for each freq. Is a number between 0-1.
Term
A double wall partition can increase STC to ___db
Definition
60db
Term
What does a double wall partition do?
Definition
completely physically isolates one side of the wall from the other, making it very difficult for sound wave vibrations to pass through the structure.
Term
Use of metal studs generally improves isolation by ___db.
Definition
5db
Term
Isolations principle tool is ____
Definition
Mass
Term
True or False: Acoustically treating a room helps isolation.
Definition
False, you stupid fucker.
Term
In a room, what 3 things happen to sound?
Definition
reflection, absorption, diffusion.
Term
What is diffusion?
Definition
The scattering of sound from a single strong discrete reflection to a broad array of lesser reflections spread in many different directions. Spreads sound evenlly while eliminating audible discrete echoes.
Term
Frequencies under 300 hz cause what problem in a room, and what are the solutions?
Definition
Standing waves. Fix with Bass traps, membrane absorbers, and helmholtz resonators
Term
Frequences over 500 hz cause what problem in a room, and what are the solutions?
Definition
Flutter echo. Fix with absorbers and diffusors.
Term
When were diffusors invented?
Definition
1970's
Term
What are the 3 types of absorbers
Definition
Flexoral, frictional, resonant.
Term
What kind of absorber uses heat and is good around 125hz-500hz
Definition
Friction
Term
How do you improve friction absorbers?
Definition
Make them thicker or move them 3-6" from wall. Moving improves them around 3-6"
Term
Why does moving a friction absorber away from the wall improve it?
Definition
6" is 1/4 of a 500hz WL.
Term
In a WL, the highest point(1/4 through the full cycle) is what 3 things?
Definition
Antinode, max compression, max pressure
Term
In a WL, the midpoint(1/2 through the cycle) is what 2 things?
Definition
Node, max velocity
Term
What type of absorber is flexoral
Definition
membrane
Term
What kind of absorber can be tuned?
Definition
Flexoral
Term
What range of Freq's are flexorals good at?
Definition
125hz-500hz
Term
What does a flexoral absorber do to freqs above 500hz?
Definition
Reflects
Term
How does a helmholtz resonator work?
Definition
The resonant absorber consists of an enclosed volume of air tuned to a low freq, with gaps or openings that allow low freq sound energy in. The air inside acts ke a type of spring on the columns of air entering the slots. The cavity can also be filled with frictional absorbent, with the effect of widening the bandwith of effective absorption to more generally absorb low freqs.
Term
Are helmholtz resonators broad or narrow band
Definition
narrow
Term
Who is sabine
Definition
Worked on reverb time, figured out rb60 formula.
Term
what is rb60
Definition
number of seconds required for the intensity of the sound to drop from the starting level, by an amount of 60 dB
Term
What is the point of acoustically treating a control room?
Definition
To hear only the sound coming out of the monitors
Term
What is a flutter echo
Definition
rapidly repeating echoes at high frequencies, which occur in small enclosed spaces between closely spaced parallel walls.
Term
A0
Definition
27.5hz, lowest note of piano
Term
C1
Definition
31.5hz, lowest C on piano, 1st band in a graphic EQ
Term
C4
Definition
261.63, middle c
Term
C8
Definition
highest C on piano, 4186hz
Term
Speed of sound
Definition
1130 ft/s, 1 ft/ms
Term
Fourier analysis
Definition
breaking down sound into individual sine waves
Term
FFT
Definition
Fast Fourier Transform, analyzing sound with 3d graph showing all the freqs
Term
What are the 10 bands of an eq?
Definition
C1- 31.6
C2- 63
C3- 125
C4- 250
C5- 500
C6- 1k
C7- 2k
C8- 4k
C9- 8k
C10-16k
Term
What is the Freq range of a piano?
Definition
27.5hz to 4186hz
Term
Haas effect
Definition
The brains ability to locate a sound source due to it's earlier arrival to one ear than the other.
Term
Peak
Definition
Highest pressure/amplitude
Term
RMS
Definition
Root Means Squared. Average Amplitude.
Term
Crest Factor
Definition
The Difference between RMS and Peak
Term
Transverse waves
Definition
Displacement is perpendicular to motion. String wave. NOT A SOUND WAVE
Term
Longitudinal waves
Definition
IS a sound wave. displacement is parallel to motion. Areas of compression and rarefaction.
Term
Phase.
Definition
The phjase of a periodic wave refers to it's current position with respect to the completetion of a full cycle, measured in degrees. 360 degrees in a cycle.
Term
Period
Definition
the time it takes for a wavelength to complete once cycle
Term
JND
Definition
Just noticable difference. Between 0.5 db and 3db
Term
Inverse square law
Definition
2x distance from sound source= -6db
Term
Frequency of Alternating current power in USA
Definition
60hz
Term
Frequency of Alternating current power in EU
Definition
50hz
Term
10x power = ___db
Definition
+10 db
Term
2x loud = ___db
Definition
+10db
Term
2x SPL= ___db
Definition
+6db
Term
2x distance
Definition
+6db
Term
2x voltage
Definition
+6db
Term
2x power = ___db
Definition
+3db
Term
10 watts 2x loud = ___ watts
Definition
100w
Term
10 watts 2x power = ___db
Definition
+3db
Term
90db 2x power = ___db
Definition
93
Term
90 db 2x loud= ___db
Definition
100 db
Term
90 db 10x power= ___db
Definition
100 db
Term
106dbSPL 2xSPL= ___db
Definition
112 dbSPL
Term
phons
Definition
the line where everything sounds as loud as a 1khz freq
Term
Parts of Outer ear
Definition
Pinna, Ear Canal, tympanic membrane (eardrum)
Term
Parts of Middle ear
Definition
Hammer, Anvil, Stirrup
Term
Parts of Inner Ear
Definition
Cochlea, Round Window, oval window, basilar membrane, stereo cillia(hairs), periymph (fluid)
Term
What freqs do the base and tip of the cochlea pick up?
Definition
Base: high freq, Tip: low freq
Term
Critcal bands
Definition
Parts of the ear that determine d
Term
3 Ways to avoid masking
Definition
EQ (2 guitars, change eq on one guitar), Pan, Arrangement
Term
below 35ms difference in arrival time to ears
Definition
delay
Term
above 50ms difference in arrival time to ears
Definition
echo
Term
between 35-50ms difference in arrival time to ears
Definition
ambience
Term
5 kinds of stereo miking
Definition
xy, spaced pair, blumlein, NOS, ORTF
Term
When did bbc begin regular stereo broadcasts
Definition
1958
Term
3 interaural cues
Definition
phase,spectrum, intensity
Term
On a SPL meter, use dbA weightings for ___ level sounds
Definition
low
Term
On a SPL meter, use dbC weightings for ___ level sounds
Definition
High
Term
Mixing domains
Definition
Level, Frequency, Space
Term
Dynamic Processing
Definition
Compression, limiting, dither
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