Hearing Science Exam 1

Front 1

sound

Back 1

vibration or displacement of air molecules caused by a disturbance/pressure

Front 2

three components necessary for sound production

Back 2

1. energy source (human body)

2. something capable of vibrating (vocal folds)

3. a transmitting medium (air)

Front 3

elasticity

Back 3

tendency for air molecules to return to their original position

Front 4

longitudinal waves

Back 4

(sound) particles displaced parallel to the energy transport (wave moves left to right)

Front 5

transverse waves

Back 5

particles displaced perpendicular to the energy transport (up and down)

Front 6

inertia

Back 6

(body in motion remains in motion) air molecules overshoot their original position and continue moving

Front 7

movement of sound

Back 7

1. air molecules set into vibration by a disturbance (vibrating source)

2. Displaced molecules collide with other molecules close to them causing them to move in a domino effect

3.elasticity causes first group to move back towards original position

4. inertia causes first group to overshoot the original position

5. elasticity brings the molecules back towards original position again (neutral)

6. process would repeat itself forever unless it encountered resistance

Front 8

damping

Back 8

resistance (heat, objects etc.) that cause air molecules to have less energy and stop vibrating

Front 9

propogation

Back 9

transportation of sound energy through each molecule

Front 10

simple harmonic motion

Back 10

perfectly periodic repeating vibration that creates a pure tone (tuning fork) equal positive and negative displacement

Front 11

maximum positive displacement

Back 11

farthest distance a molecule travels away from its neutral position towards the positive side

Front 12

maximum negative displacement

Back 12

farthest distance a molecule travels away from the neutral position towards its negative side

Front 13

sine/sinusoidal waves

Back 13

waveform that results from a simple harmonic motion (rarely occurs in nature/repeats itself perfectly)

Front 14

amplitude/intensity

Back 14

how much the molecule has been displaced from the neutral point (the greater the displacement, the more intense a sound is) how much it is vibrating

Front 15

cycle of a sine wave

Back 15

one complete transition of a sine wave:

1. neutral

2. max pos displacement

3. neutral

4. max neg displacement

5. neutral

Front 16

period

Back 16

time it takes to complete one full cycle (T in milliseconds) convert to seconds by dividing by 1,000 before calculating freq

Front 17

frequency

Back 17

number of complete cycles that occur in one second (inverse of how long it takes to complete one cycle or period)

Hz (cycles per sec) f= 1/T

Front 18

phase

Back 18

the point in the cycle that a vibrator is located at a given time (defined in the angles of a circle 0-360)

Front 19

high frequency

Back 19

shorter period, more cycles per second

Front 20

low frequency

Back 20

longer period, fewer cycles per second

Front 21

pure tones

Back 21

sounds produced by air molecules in simple harmonic motion (energy is concentrated all at one frequency of air molecule vibration)

Front 22

four ways of measuring amplitude

Back 22

1. instantaneous

2. peak amplitude

3. peak to peak

4. root mean square (RMS)

Front 23

instantaneous amp

Back 23

amplitude at a specific point in time

Front 24

peak amplitude

Back 24

measure the displacement in one direction (positive or negative)

Front 25

peak to peak amplitude

Back 25

measure amplitude/displacement from max pos displacement to max neg displacement

Front 26

root mean square amplitude

Back 26

measure the square root of the average of all amplitude squared (.707 x peak amplitude)

Front 27

condensation/compression

Back 27

air molecules are bunched together tightly (high pressure)

Front 28

high pressure

Back 28

occurs when air molecules are bunched together tightly, closer they are, the more likely they are to collide

Front 29

rarefaction/low pressure

Back 29

air molecules are spread apart, less likely to bump into eachother

Front 30

wavelength

Back 30

distance a wave travels during one complete cycle of vibration

w= c/f

c=velocity (344)

Front 31

wavelength depends on...

Back 31

1. frequency of vibration (higher freq-shorter wavelength)

2. velocity of sound in a medium

Front 32

intensity

Back 32

pressure that the vibrating object exerts on an area

dyne/cm2

pure tone intensity determined by amplitude

(loudness is psychoacoustic correlate)

Front 33

decibel

Back 33

measurement of intensity on a logarithmic scale

0-140 dB SLP converting .0002 d/cm2 and up to decibels

20 x log ratio of pressure measure divided by reference point (.0002)

Front 34

logarithmic scale (decibels)

Back 34

based on exponents, base of 10, increments are not equal but condenses the scale into more readable/understandable numbers

Front 35

decibel conversion formula

Back 35

20 log (pressure measured/.0002)

Front 36

why use a log scale for decibels?

Back 36

log scale represents how ear hears changes in sound pressure

doubling the pressure does NOT double the loudness, you would need to triple the pressure and increase 10 dB

Front 37

simple sound

Back 37

energy concentrated on one frequency/equal displacement in pos and neg directions

Front 38

complex sound

Back 38

multiple frequencies combined to make one complex waveform

Front 39

waveform

Back 39

picture of a wavelength, shows how many cycles repeat

Front 40

spectrum

Back 40

breaks down the cycle into the frequencies that make up the waveform

Front 41

fourier's theorem

Back 41

complex periodic waveform is made up of multiple simple periodic waveforms

Front 42

adding sine waves to make a complex wave

Back 42

1. when two peaks occur together add them (either positive or negative)

2. when one peak is pos and one peak is neg they cancel out

Front 43

harmonics

Back 43

frequencies present in a complex sound

higher freqs occuring at each multiple of the fund freq (ex. 100, 200, 300)

Front 44

fundamental frequency

Back 44

the lowest frequency present in a complex sound (f0)

Front 45

pitch

Back 45

repetition rate of a pattern

perceptual correlate of frequency

doubling in freq does not equal doubling in pitch

Front 46

octave

Back 46

doubling in frequency

Front 47

timbre

Back 47

relative amplitude of each harmonic to the fundamental (quality of a sound)

Front 48

formant frequencies

Back 48

harmonics with the greatest peak amplitude

help us distinguish between vowels because different vowels have peak amplitudes at different frequencies

Front 49

sawtooth waveform

Back 49

complex periodic waveform (similar to vocal fold vibration)

immediate transition from positive (compression) to negative (rarefaction)

Front 50

periodic

Back 50

repeats in time (can be simple or complex and has a pitch associated with it)

Front 51

aperiodic

Back 51

doesn't repeat in time, no pattern

can be classified as transient, continuous but random

no pitch associated with it

Front 52

noise

Back 52

aperiodic, continuous but not repeating

two types: broadband and narrowband

Front 53

transient

Back 53

comes and goes very quickly (click) not continuous

Front 54

broadband noise

Back 54

made up of a broad range of many random frequencies

ex. white noise, pink noise

Front 55

white noise

Back 55

continuous aperiodic broadband noise with all possible frequencies present

Front 56

pink noise

Back 56

continuous aperiodic broadband noise with amplitude that decreases (roll of of 3db with every doubling of freq)

Front 57

type of noise depends on...

Back 57

1. the frequencies that make it up (BBN vs. NBN)

2. the amplitude of frequencies that make it up( white noise vs. pink noise

Front 58

narrowband noise

Back 58

made up of limited frequencies

Front 59

bandwidth

Back 59

measure of the range of frequency components in a sound

Front 60

tone burst

Back 60

shortened pure tone, aperiodic, short duration, not continuous, very quick rise and fall times ( the time it takes to get to max amp)

Front 61

click

Back 61

brief pulse with an instantaneous onset, not continuous, aperiodic, broad spectrum (contains energy across a wide variety of frequencies)

Front 62

inverse square law

Back 62

with no obstacle, the farther away the sound source, softer the sound becomes

for every doubling of distance (in meters) from the source, sound intensity decreases by 6 dB

Front 63

constructive interference

Back 63

the amplitude of the resultant waveform is greater because the two component waves are in the same phase and have added together

Front 64

destructive interference

Back 64

occurs when two waves are not in the same phase and cancel eachother out, amp of resultant wave has decreased

Front 65

standing wave

Back 65

product of a reflected wave moving back in the opposite direction and overlapping with original wave that creates points of constructive and destructive intereference=wave just oscillates does not actually move

Front 66

in phase

Back 66

when two compression or rarefaction valleys meet, they add together

Front 67

out of phase

Back 67

when two compression and rarefaction valleys meet they cancel out

Front 68

interference of long wavelengths

Back 68

long wavelengths (low freq) can bend around objects (only lose intensity due to distance)

Front 69

interference of short wavelengths

Back 69

short wavelengths (high freq) can't bend around objects so they get absorbed and converted to heat energy, are reflected back or they travel around the object and lose intensity

Front 70

soundfield

Back 70

no headphones

Front 71

anechoic room

Back 71

room made so that there is no reflection

Front 72

reverberation

Back 72

prolongation of a sound's intensity after it has been turned off

Front 73

reverberation time

Back 73

amount of time it takes a reverberated sound to die down

Front 74

standing in a point of destructive interference in soundwave

Back 74

you hear absolutely nothing

Front 75

standing in a point of constructive interference in a soundwave

Back 75

you hear a sound with increased intensity

Front 76

reflection

Back 76

when a wave enounters a dense wall (not absorbed) it will be reflected/bounces off with a 180 degree phase change and adds constructively to original wave

Front 77

antinodes

Back 77

points of changing displacement(amplitude), able to hear sound

Front 78

nodes

Back 78

points of no displacement (you hear nothing)

Front 79

acoustic resonator

Back 79

a hollow space/cavity that amplifies certain frequencies and dampens others because of its shape

abnormally large vibration is produced by an external stimuli who's freq matches the natural vibration freq of the resonator

Front 80

resonant frequency

Back 80

natural vibration of the resonator (peaks in spectrum)

Front 81

resonant freq of tube open at one end and closed at the other

Back 81

tube will resonate when the wavelength is 1/4 the length of the tube (or an integer multiple of this)

wavelength=4(L+.8d) freq=c/4(L+.8d)

Front 82

resonant freq of a tube open at both ends

Back 82

tube will resonate when the wavelength is 1/2 the length of the tube (or an integer multiple of this)

freq=c/2(L+0.8d)

Front 83

filter

Back 83

resonator that passes some frequencies(resonates at these frequencies) and rejects some frequencies (does not resonate at these frequencies)

Front 84

highpass filter

Back 84

passes filters above a "cutoff" freq and rejects those below the cutoff freq

Front 85

bandpass filter

Back 85

passes/resonates at frequencies in between two cutoff frequencies

Front 86

spectograms

Back 86

frequency by time graph with intensity marked by colors (red-intense, blue-least intense)

Front 87

source filter theory

Back 87

sound comes from the source (glottis/vibrating vocal folds) and is filtered by the vocal tract/articulators ultimately creating a new output sound

Front 88

non linearity

Back 88

a filter can not only modify sounds but can also add other frequencies to the sound source