# Shared Flashcard Set

## Details

acoustics final
final for music acoustics
50
Physics
12/15/2011

Term
 In modern cinema, digital sound is reproduced in the theater from _____
Definition
 a compact disk synchronized to the film.
Term
 A certain sound card digitizes the sound at a sampling rate of 22.2 kHz. According to the Nyquist Criterion, what is the maximum frequency that can be faithfully recorded by this sound card?
Definition
 Approximately 11 kHz
Term
 In a vinyl LP record, the acoustic information is stored as ___________________
Definition
 Analog variations in the depth and width of the groove.
Term
 In a tape cassette recorder, the sound information is recorded as ____________
Definition
 fluctuations in the direction and magnitude of small magnetic fields.
Term
 A dynamic microphone uses ___________
Definition
 a small coil attached to a diaphragm that moves in a magnetic field.
Term
 A condenser mic _____________
Definition
 uses the variation in the distance between two conducting diaphragms to produce an electrical signal that is the analog of the sound pressure fluctuation.
Term
 The number 9 ("nine") is correctly represented by which of the following binary numerals?
Definition
 [1001]2
Term
 A cardioid microphone ________
Definition
 is much more responsive to sounds coming from one direction because of interference effects.
Term
 The secret of digital electronics is ________
Definition
 simple two-state (on or off) switches arranged in complicated circuits.
Term
 Sound is _____________
Definition
 energy propagating by means of longitudinal waves produced by a vibrating object.
Term
 What is the speed of a 1kHz sound wave in air at 37 C?
Definition
 353m/s
Term
 An automobile is running over the rumble strips at the side of a highway. If the tire runs over a bump once every 33.3 milliseconds, what is the frequency of the sound wave that the tire will emit?
Definition
 440 Hz
Term
 What is the wavelength of a sound wave in air (assume 20C) from a tuning fork labeled "A4 440 Hz"?
Definition
 Approximately 0.78 m
Term
 A supersonic plane travels at Mach 2.0 (twice the speed of sound). How fast is this? (Hint: 1 m/s = 2.24 mph).
Definition
Term
 What is the frequency of a sound wave that has a wavelength at 53C (v = 363 m/s) of 1 meter?
Definition
 approximately 363 Hz
Term
 Wavelength is ______________
Definition
 the distance from one point on a wave to the corresponding point on the next cycle.
Term
 What is the fundamental of a harmonic series that contains the following frequencies: 440, 880, 1320?
Definition
 440 Hz
Term
 If one doubles the spring constant k in a simple harmonic oscillator, what happens?
Definition
 The frequency increases by a factor of about 1.414.
Term
 When the Comet Shoemaker-Levy 9 crashed into Jupiter in 1994, creating a hole the size of the earth, why did we not hear it in Denton?
Definition
 Sound waves cannot travel through a vacuum because there is no matter to oscillate.
Term
 What is Ohm's Law for acoustics?
Definition
 The human ear is insensitive to the phase of sound waves.
Term
 A phon is ___________
Definition
 a unit of perceived loudness level.
Term
 The human ear senses the frequencies in a sound by ______________
Definition
 the resonances of the basilar membrane in the cochlea.
Term
 The Fletcher-Munson diagram plots _________
Definition
 the sound intensity level corresponding to various perceived loudness levels as a function of frequency.
Term
 What is the threshold for hearing in dB?
Definition
 0 dB
Term
 What happens to the perceived pitch if a sustained low note is played loudly?
Definition
 It sounds flat
Term
 In recording and electronic amplification equipment there is a "VU" meter that measures the intensity of the sound in "volume units" or decibel. How much more intensity is a VU reading of 20 dB than one of 10 dB?
Definition
 10 times
Term
 In the plot of the SIL versus time below for a room, what is the approximate reverberation time?   [GRAPH]
Definition
 2.4 sec
Term
 If a room has an effective absorption area of Se = 800 Sabine when it is empty, and the reverberation time is 2 sec, what will happen when an audience of 1000 people is added? (Assume the effective area of a person is .8 Sabine)
Definition
Term
 Before a rock concert begins, a sound engineer measures the SIL of a speaker to be 110 dB (.1W/m2) at a distance of 10 m from a loud speaker. What will be the approximate SIL due to this speaker alone at 100 m, where you stand, if everything else is the same?
Definition
 1 x 10^-3 W/m2 (80 dB)
Term
 The effect of the mouthpiece and the bell is to alter the harmonic sequence of a trumpet, such that _________________
Definition
 the lowest freq. is often not harmonic w/ the overtones.
Term
 Just temperament is based on ____________
Definition
 ratios of small whole #s
Term
 What is the approx. fundamental freq. of a guitar string .62 m long stretched w/ a tension of 100 N and for which 1 m of the string has a mass of .006 kg?
Definition
Term
 In the equal tempered scale, the ratio of notes that are a semitone apart.
Definition
 1.05946
Term
 What is the approx. fundamental freq. of C5 if A4 is tuned to 440 Hz on the equal tempered scale.
Definition
 523 Hz
Term
 A cent is what part part of a semitone interval?
Definition
 1/100
Term
 According to Fourier, into a series of what wave type can all periodic waveforms be decomposed?
Definition
 sine wave
Term
 When you add water to a bottle and blow across it's mouth, ________________
Definition
 the freq. gets higher b/c the "air spring" is stiffer
Term
 What is the approx. freq. of a SIL w/ m=.5 kg and K=1.6 x 10^6 N/m?
Definition
 285 Hz
Term
Definition
 the audio signal is encoded in the radio wave amplitude or freq.
Term
 Standing wave formation inside a tube of uniform cross section is mostly attributable to
Definition
 Longitudinal sound wave reflection at the boundaries.
Term
 Near the open end of an air column in vibration, there would be both
Definition
 a pressure node and a displacement anti-node
Term
 In an open cylindrical organ flute pipe played at 20 C, what is the approx. freq of the first overtone if the pipe is 1.5 m long?
Definition
 114 Hz
Term
 What is the approx. fundamental freq. of a pan pipe played at 20 C and that is 19.5 cm long?
Definition
 440 Hz
Term
 In an ideal open tube of cylindrical cross section
Definition
 only odd members of a harmonic series can exist
Term
 In reed instruments,
Definition
 The reed end is treated as a closed end, but instrument with a conical bore like the sax, allows the instruments to play all harmonics
Term
 Valve sounds from the human voice can be characterized by their formants.
Definition
 Formants are broad resonance bands of the vocal tract.
Term
 The pitch of the human voice is caused by:
Definition
 The vibration modes of the vocal folds
Term
 Vibration modes on a drum membrane
Definition
 Are generally inharmonic
Term
 The cheif difference between a xlyophone and a marimba
Definition
 the marimba has a deeper and wider undercut
Term
 A natural horn such as a bugle
Definition
 Changes pitch by the lips at different frequencies. Ally hany if you miss this one you are an idiot. Sincerely, Addison
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