Week 1 - Acoustics

Question 1

Sound waves

Answer 1

compressions and rarefactions of air molecules

Question 2

Compressions

Answer 2

Regions of increased density

Question 3

Rarefactions

Answer 3

Regions of decreased density; restorative force and momentum

Question 4

Waveform

Answer 4

Graphical display that represents the alternating compressions and rarefactions of air molecules that make up the longitudinal sound pressure wave

Question 5

Airborn sound waves

Answer 5

Generated by a mechanical source - rapid vibration in air pressure

Question 6

Periodic waves

Answer 6

Regular, repeating pattern of compression and rarefaction

Sound source is vibrating at a regular rate (F0)

Question 7

Aperiodic waves

Answer 7

Mechanical source without regular/oscillating movement

Question 8

Simple waves

Answer 8

Pure tones, sine waves
Consists of one tone
Not naturally occuring

Question 9

Complex sound waves

Answer 9

More than one frequency
Either aperiodic/periodic
Combination of sine waves, each with own frequency, amplitude and phase

Question 10

Frequency

Answer 10

Number of oscillations in a second
Measured in hertz 
Can hear 20-20 000Hz
Less cycles/sec = lower Hz, lower pitch
High cycles/sec = higher H, high pitch

Question 11

Air pressure

Answer 11

Amount of change in air pressure from sound
Relates to vertical height of waveform
Measured in Pascals, Dynes/cm^2

Question 12

Decibel scale

Answer 12

Sound pressure and intensity simplified into 140 units

0-140dB threshold of hearing

Question 13

Conversation - dB

Answer 13

60dB

Question 14

Pain threshold - dB

Answer 14

130-140dB

Question 15

Period

Answer 15

Amount of time taken to complete one cycle

Can measure duration of vowels, words, pauses during connected speech

Question 16

Velocity

Answer 16

Speed at which the sound wave travels through a medium

wavelength = velocity/frequency

Question 17

phase

Answer 17

Starting point of one cycle of tone/frequency

Question 18

Wave length

Answer 18

distance travelled by one cycle of the waveform

wavelength = velocity/frequency

Question 19

Decibel Scale

Answer 19

shows how loud a sound is relative to the threshold of hearing
Can be measured according to sound pressure level (SPL)/sound intensity (SI)
Consists of 140 points

Question 20

Fundamental frequency

Answer 20

Main, lowest oscillation frequency of mechanical source

Question 21

Harmonic Spectrum

Answer 21

Multiples of the fundamental

Consists of the F0 and higher harmonic frequencies

Question 22

Vowel features - frequency

Answer 22

Periodic, therefore have periodic soundwave features;

F0 and harmonic frequencies

Question 23

Pitch

Answer 23

Psychological correlate of F0

Question 24

Loudness

Answer 24

Psychological correlate of amplitude

Question 25

Timbre/quality

Answer 25

Psychological correlate of sound complexity

Question 26

Psychophysical scaling

Answer 26

quantifies psychological dimensions of the physical properties of sound

Question 27

Sone

Answer 27

Psychological scale of loudness

Question 28

Mel

Answer 28

Psychological scale of pitch

Question 29

Spectral Analysis

Answer 29

Analyses of the simple sine wave components making up complex sound
Spectrum = freq, amplitude, phase

Question 30

Spectral Analysis - periodic vs aperiodic

Answer 30

Periodic - evenly spaced peaks

Aperiodic - no peaks

Question 31

Pitch Analysis Methods

Answer 31

Cross Correlation

Autocorrelation

Question 32

Problems with analysis

Answer 32

provide highly inaccurate estimates of F0; due to background noise, disordered voice, inappropriate set up for pitch analysis

Question 33

Psychological correlates - frequency

Answer 33

pitch

Question 34

Psychological correlates - amplitude

Answer 34

loudness

Question 35

Psychological correlates - complexity

Answer 35

quality/timbre

depends on harmonic content, dynamic characteristics