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Auditory area

range of human hearing; 20-20000 Hz

Decibel

unit of measurement for sound intensity

Decibel scale

a logarithmic ratio scale that compares the amplitude and/or intensity of target sound to a standard reference sound; a logarithmis scale is used to measure intensity

Frequency

rate of vibration of an object; number of cycles per second of a sound wave

Intensity

power per unit area

Inverse square relationship

intensity varies inversely with the distance from the source; intensity is decreased by the square of the distance change factor

linear scale

scale by which successive unit sincrease by the same amount

logarithmic scale

scale in which successive units increase by increasing amounts

loudness

perceptual correlate of intensity

mel scale

unit of putch on a psychophysical scale; a perceptual, subjective scale for pitch

phon scale

a psychoacoustic scale for intensity that uses a 1000 Hz pure tone as the reference frequency; subjective scale for loudness

pitch

the perceptual correlate of frequency

psychoacoustics

study of the relationship between the phsycial properties of a stimulus and our subjective experience of the stimulus

ratio scale

scale that describes relationships between quantities

semitone scale

Western musical scale consisting of 12 pitches, each separated by a semitone

standard reference sound

sounds with amplitude of .0002 dyne/cm2 and intensity of 10-16 W/cm2

subsonic

frequencies below the range of human hearing

supersonic

frequencies above range of human hearing

threshold of hearing

sound that a pair of normal human ears can detect 50% of the time under ideal listening conditions

threshold of pain

intensity level of 130 dB, which causes of sensation of pain in the ears

compression

area of positive pressure; collistions of air molecules result in regions of increased density

displacement force

force that cuases a mass to be moved away from equilibrium

equilibrium

a state in whihc opposing dynmaic forces balance each other

longitudinal wave

the particles of the medium move parallel to the direction of the wave

mechanical wave

a wave that requires a medium to propagate itself - sound wave

oscillation

back and forth movement of an object; vibration

pulse wave

a single disturbance travels through a medium

rarefaction

area of negatieve pressure; regions of decreased density of air particles

restorative force

force that causes a mass to return to equilibrium

sound wave

a mechanical, longitudinal pressure wave that transmits sound

transverse wave

the particles of the mediym move perpendicularly to the direction of the wave

vibration

oscillation, a back and forth cyclic movement about some point

absorption

damping of a wave with diminishing changes in air pressure due to friction

boundary

interface between two mediums

constructive interference

waves that combine and increase the amplitude of the resulting wave; amplifies the rarefaction or an area of compression

destructive interference

waves that combine and decrease the amplitude of the resulting wave; a wave interferes with another wave such that a compression of one wave meets a rarefaction of the other wave and the net effect is to decrease the overall energy

diffraction

the sound wave bends around an obstacle without going through the boundary

interference

combining of waves in terms of areas of high and low pressure

incident wave

sound wave generated by a vibrating object

refraction

the change in the speed and direction of a sounds wave due to inteaction iwith a boundary

reflection

wave that collides with a surface and travels back toward the source; the sound wave bounces backward off the boundary

reflected wave

the portion of the energy of a sound wave that returns back after meeting a boundary

reverberation

process generating a sound that last slightly longer due to interaction of incident and reflected waves

standing wave

a pattern restulting from the interference of an incident and a reflected sound wave that apprears to be standing still

wave front

outermost area of the sound wave propagating spherically through the air

amplitude

the amount of displacement of an object from its rest position; magnitude of oscillation or height of wave

aperiodic

wave in which cycles do not take the same amount of time to occur; irregular sound wave

complex aperiodic sound

a sound wave consisting of multiple frequencies in which the cycles do not take the same amount of time to occur

complex periodic sound

a sound wave consisting of multiple frequencies in which the cycles take the same amount of time to occur

complex sound

sound with two or more frequencies; a sound wave consisting of two or more pure sounds

cycles per second

number of cycles of vibration occurring in one second, equivalent to frequency

fundamental frequency

lowest frequency of a complex periodic sound; the repetition frequency of a sine wave or a complex pattern

harmonics

frequencies above F0 in a complex periodic sound, which are integer multiples of the fundamental frequency

Hertz

unit of measurement of frequency (cycles per second)

Quasiperiodic

a sound wave consisting of multiple frequencies in which the cycles do not take exactly the same amount of time to occue, but a repetitive pattern is apparent

period

amount of itme consumed by each cycle in a wave; the reciprocal of the frequency, the duration of one cycle

periodic

wave in which each cycle take the same amount of time to occur

phase

relative timing of compressions and rarefactions of waves; the point in the cycle of cibration at which the waveform begins

pure tone

sound with only one frequency; a sound wave consisting of energy at a single periodic frequency

simple harmonic motion

a smooth back and forth movement with a characterstic pattern of acceleration though the rest position and deceleration at the end-points of the movement; unifrom ciruclar motion or perioidc motion around a central equilibrium point

Sine wave

pure tone with a sinusoidal shape on a waveform; the simplest waveform

waveform

graph with time on the horizontal axis and amplitude on the vertical axis

wavelength

distance covered by one complete cycle of a wave; distance covered by one cycle of vibration

continuous spectrum

spectrum that contains energy at all frequencies

envelope

line that connects the frequencies of a complex sound represented on a spectrum; contour formed by the distplay of engery at each frequency represented in a sound wave

fourier analysis

mathematical procedure to identify the individual sinusoids in a complex sound; a complex mathematical process of decomposing a complex wave into its separate sine waves; a method to transfer the time-series speech waveform into a frequency-based spectrum

line spectrum

graph in which the frequencies in a complex periodic sound are depicted as vertical lines, where the height of the line indicates the amplitude of the compenent frequency

power spectrum

a plot of the power (energy per unit of time) of given frequencies of a sound (same as a line spectrum)

spectrum

graph with frequnecy on the horixontal axis and amplitude on the vertial axis; line spectrum represents periodic sounds, continuous spectrum represents aperiodic sounds