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22 Cards in this Set
- Front
- Back
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Inverse square law
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The loss of intensity of sound; formulated as I = Power/4 π r ²
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Area of a sphere
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A = 4 π r ²
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Equation for calculation of inverse square intensity loss.
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At a point R, intensity is Iₐ. At 2r, intensity is Iₐ/4. At 3r, intensity is Iₐ/9. Therefore, intensity loss is Ia/Multiple of R squared.
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Conversion of ΔI to dB.
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Take the denominator of the equation for inverse square loss of intensity, write that number as a factor of 10, add a zero to this number, and subtract this final number from Iₐ in dB.
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Bass Loss Problem
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The ear's tendency to discriminate against bass sounds as sound gets softer.
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Formula for intensity at the surface of a sphere.
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P/4 π r^2
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Ideal listener spot.
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The part of the auditorium that is the model for all sound mixing for the rest of the auditorium.
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Overcoming Inverse Square Law by architecture
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Accomplished by using echos to reinforce sound for listeners that are not in the ideal listener spot.
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Reverberation Time
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The time it takes for a sound to drop 60 dB below the initial sound level. Notated as RT₆₀. Measured as such for the loudest crescendo (roughly 100 dB) minus room background noise (40dB).
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Optimal Reverberation Time for a general purpose auditorium
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2 seconds. Any more than 2 seconds will increase richness of sound but begins to decrease articulation. Any less will give clearer articulation but make the room acoustically dead.
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Optimal Reverberation Time for a lecture auditorium.
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Less than a second.
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Factors of long reverberation time.
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Reflective surfaces.
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Optimal reverberation time for a studio
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As close to acoustically dead (0 seconds) as possible.
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First sound researcher in the world.
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Wallace Sabine
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Sabine (unit measurement)
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A unit of absorption.
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Methods of dealing with Bass Loss
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Add more reverberation time to bass frequencies.
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Sound loss at factors of 2.
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Roughly 6 dB. Thus, in distance from sound source 2ft = 80 dB, 4ft = 74dB, 8ft = 68 dB, etc.
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Maximum allowable feedback loop.
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The maximum allowable output of feedback into a microphone is the same as is put into the microphone in the first place.
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PAG stands for...
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Potential Acoustic Gain
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Methods of increasing PAG.
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moving closer to microphone, moving speakers further from microphone, use digital delay, directional microphones and loudspeakers, use a feedback suppressor,
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100 cents is equal to...
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One equal-tempered semi-tone
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Temperature changes affect an instrument by how much?
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1.6 cents for every 1 degree F
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