| HVAC:| what does it stand for and what are the 3 things it causes? |
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| Heating, Ventilation, Air conditioning.
Noise, flanking(noise brought in from another room through the ac vents), wind. |
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| 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 |
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| 6 foot gobo, what freqs can it block? |
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definition: diffraction
Why does it happen? |
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| 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. |
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| Lower Frequency means longer or shorter WL? |
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Mass Law: 2 times the mass equals
___db increase in isolation |
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Mass Law: half the mass equals
___db decrease in isolation |
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| What does TL stand for? And what is it? |
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| Transmission Loss. A specific ratio in db between energy that goes in and goes out. The higher the TL, the better the isolation. |
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| TL of 500hz 36 db. Sound going in is 100 db. How loud is the sound coming out? |
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| 2x freq = ___db change in TL |
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| 1/2 freq = ___ db change in TL |
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| 2x mass = ___db change in tl |
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| What does STC stand for and what is it? |
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| Sound Transmission Class. A single number rating covering the TL performance of a construction between 125hz and 4khz. |
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| Is STC a ratio or a single number? |
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| 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? |
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| What does NRC stand for and what is it? |
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| Noise Reduction Coefficient. An average rating of noise reduction. Average of 250hz,500hz,1khz,2khz. Is a number between 0-1. |
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| NRC is an average rating through what freqs? |
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| Is NRC specific or broad? |
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| Is A.C. specific or broad? |
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| Do TL and STC say anything about low frequencies? |
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| What does AC stand for and what is it? |
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| Absorption Coefficient. A specific rating for each freq. Is a number between 0-1. |
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| A double wall partition can increase STC to ___db |
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| What does a double wall partition do? |
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| completely physically isolates one side of the wall from the other, making it very difficult for sound wave vibrations to pass through the structure. |
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| Use of metal studs generally improves isolation by ___db. |
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| Isolations principle tool is ____ |
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| True or False: Acoustically treating a room helps isolation. |
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| False, you stupid fucker. |
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| In a room, what 3 things happen to sound? |
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| reflection, absorption, diffusion. |
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| 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. |
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| Frequencies under 300 hz cause what problem in a room, and what are the solutions? |
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| Standing waves. Fix with Bass traps, membrane absorbers, and helmholtz resonators |
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| Frequences over 500 hz cause what problem in a room, and what are the solutions? |
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| Flutter echo. Fix with absorbers and diffusors. |
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| When were diffusors invented? |
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| What are the 3 types of absorbers |
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| Flexoral, frictional, resonant. |
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| What kind of absorber uses heat and is good around 125hz-500hz |
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| How do you improve friction absorbers? |
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| Make them thicker or move them 3-6″ from wall. Moving improves them around 3-6″ |
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| Why does moving a friction absorber away from the wall improve it? |
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| In a WL, the highest point(1/4 through the full cycle) is what 3 things? |
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| Antinode, max compression, max pressure |
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| In a WL, the midpoint(1/2 through the cycle) is what 2 things? |
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| What type of absorber is flexoral |
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| What kind of absorber can be tuned? |
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| What range of Freq’s are flexorals good at? |
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| What does a flexoral absorber do to freqs above 500hz? |
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| How does a helmholtz resonator work? |
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| 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. |
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| Are helmholtz resonators broad or narrow band |
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| Worked on reverb time, figured out rb60 formula. |
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| number of seconds required for the intensity of the sound to drop from the starting level, by an amount of 60 dB |
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| What is the point of acoustically treating a control room? |
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| To hear only the sound coming out of the monitors |
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| rapidly repeating echoes at high frequencies, which occur in small enclosed spaces between closely spaced parallel walls. |
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| 27.5hz, lowest note of piano |
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| 31.5hz, lowest C on piano, 1st band in a graphic EQ |
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| highest C on piano, 4186hz |
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| breaking down sound into individual sine waves |
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| Fast Fourier Transform, analyzing sound with 3d graph showing all the freqs |
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| What are the 10 bands of an eq? |
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C1- 31.6
C2- 63
C3- 125
C4- 250
C5- 500
C6- 1k
C7- 2k
C8- 4k
C9- 8k
C10-16k |
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| What is the Freq range of a piano? |
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| The brains ability to locate a sound source due to it’s earlier arrival to one ear than the other. |
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| Highest pressure/amplitude |
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| Root Means Squared. Average Amplitude. |
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| The Difference between RMS and Peak |
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| Displacement is perpendicular to motion. String wave. NOT A SOUND WAVE |
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| IS a sound wave. displacement is parallel to motion. Areas of compression and rarefaction. |
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| 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. |
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| the time it takes for a wavelength to complete once cycle |
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| Just noticable difference. Between 0.5 db and 3db |
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| 2x distance from sound source= -6db |
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| Frequency of Alternating current power in USA |
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| Frequency of Alternating current power in EU |
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| 10 watts 2x loud = ___ watts |
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| 10 watts 2x power = ___db |
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| the line where everything sounds as loud as a 1khz freq |
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| Pinna, Ear Canal, tympanic membrane (eardrum) |
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| Cochlea, Round Window, oval window, basilar membrane, stereo cillia(hairs), periymph (fluid) |
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| What freqs do the base and tip of the cochlea pick up? |
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| Base: high freq, Tip: low freq |
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| Parts of the ear that determine d |
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| EQ (2 guitars, change eq on one guitar), Pan, Arrangement |
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| below 35ms difference in arrival time to ears |
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| above 50ms difference in arrival time to ears |
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| between 35-50ms difference in arrival time to ears |
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| xy, spaced pair, blumlein, NOS, ORTF |
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| When did bbc begin regular stereo broadcasts |
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| phase,spectrum, intensity |
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| On a SPL meter, use dbA weightings for ___ level sounds |
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| On a SPL meter, use dbC weightings for ___ level sounds |
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| Compression, limiting, dither |
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