Acoustics

Question 1

pressure fluctuations

Answer 1

the difference in pressure through whatever acoustic medium is present that results in sound when the product of those movements hit the eardrum

Question 2

acoustic medium

Answer 2

whatever the sound waves are traveling through – usually air but it could also be water, helium, etc

Question 3

sound wave

Answer 3

traveling pressure fluctuation that propogates through any acoustic medium

Question 4

periodic sounds

Answer 4

sound waves that repeat at regular intervals; only young children produce periodic sounds then adult women rank between children and men in this regard

Question 5

aperiodic sounds

Answer 5

sounds aves that do not repeat at regular intervals

Question 6

frequency

Answer 6

number of times the sinusoidal pattern repeats per unit time; expressed by cycles/second = Hz

Question 7

cycle

Answer 7

the full length it takes the sound wave to return to the beginning of the frequency and start a new repetition

Question 8

period

Answer 8

the duration of a cycle

Question 9

phase

Answer 9

the timing of the waveform relative to a reference point

Question 10

simple vs complex periodic waves

Answer 10

complex waves have at least two sine waves

Question 11

power spectrum

Answer 11

a plot that shows the amplitude vs frequency plot

Question 12

Fourier’s theorem

Answer 12

a complex waveform can be broken down into the simple waveforms that make up this relationship…(the phases of the component waveforms are usually irrelevant for this analysis) –> the result is a power spectrum

Question 13

white noise

Answer 13

sound characterized by random (aperiodic) pressure fluctuation; should, in theory, result in a flat spectrum

Question 14

analysis window

Answer 14

a short chunk of the sound waves being used for speech analysis

Question 15

transients

Answer 15

type of aperiodic sound that is not sustained or repeated over time; e.g., door slams, balloon pops, electrical clicks

Question 16

resonance

Answer 16

a property of manipulating the filter that

Question 17

centroid frequency

Answer 17

like a formant but no voicing; fricatives have this property

Question 18

low pass filter

Answer 18

a type of acoustic filter that blocks the high frequency components of a wave and passes the low frequency components through

Question 19

band pass filters

Answer 19

unlike low or high pass frequencies they have two pass bands (one for the low and one for the high frequencies)

Question 20

compression vs scattering

Answer 20

compression refers to the “crowding” of air molecules = positive pressure; scattering refers to the dispersion of molecules or “rarefaction” = negative pressure