hearing and speech science

production

how sound is created/produced

propagation

how sound moves through a medium

perception

how a listener experiences/interprets sound

sound

A mechanical wave created by vibration that requires a medium to propagate

medium

the material through which sound propagates (gas, liquid, solids)

elasticity

the ability of object/medium to return to its original position after being displaced

longitudinal wave

movement of particles of the medium is in the same direction as the movement of the source of sound waves (compressiion/rarefraction)

Transverse wave

movement of the particles of the medium is perpendicular to the motion of the source (normal wave)

Compression

area where particles are close together and pressure is higher

Rarefaction

an area where particles are farther apart and pressure is lower

Speed of propagation

how quickly a sound wave moves through a medium

Frequency

the number of vibration that occurs in one second (characterstic related to pitch)

Period (T)

the time taken for one complete vibration (F = 1/T)

wavelength

the distance between particles of the medium that represent two successive peaks ( λ = velocity/frequency)

amplitude

maximum displacement of particles of medium from the average resting position

hearing

ability to detect sound, accidential, involuntary, and effortless

listening

actively paying attention to sound, focused, voluntary, and intentional

Signal to noise ratio (SNR)

the relationship between the speech/signal you want to hear and the background noise

Signal processing (SP)

how the auditory system/brain processes amd interprets the  quality of a sound

understanding

when your brain is trying to decipher sound being heard and puts meaning behind it

bottom up processing

understanding information based on the actual sensory information coming in

Top down processing

Use of prior knowledge, memory, context, and expectations to understand sound

McGurk effect

when what you see someone doing with their mouth changes what you think you hear

intensity

physical characterstics related to loudness

Timbre

the quality/tonal character of sound that helps distinguish sound from each other

simple harmonic motion

reapeated back and forth motion around an equilibrium (sine wave)

restoring force

force that brings an object/medium back toward equilibrium

qualitative

describe sound without giving numbers; loud, soft, high, or low pitch

quantitave

actual measurement/numbers; intensity, frequency

peak

the highest point of a wave above the baseline/equilibrium

trough

the lowest point of a wave below the baseline/equilibrium

pressure

physical force exerted on an object per unit area

Mach 1

the speed of sound in air

Mach 2

twice the speed of sound

Density

how much particles are packed into a given space. density of medium can affect the speed of sound

phase

the position of a point within a wave cycle

in phase

two waves have their corresponding points occuring at same times

out of phase

two waves have their corresponding points occuring at different times

phase difference

the amount by which two waves are shifted relative to each other

cycle

one complete repetiton of a wave

periodic motion

motion that repeats itself in regular patterns

uniform circular motion

motion around a circle at a constant speed

velocity

how quickly an object changes position. SHM velocity is not constant

Peak amplitude

The maximum displacement from the resting/zero position

Peak to peak amplitude

total distance from highest point to lowest point of a wave (negative to positive)

instantaneous amplitude

the amplitude at a specifc point in time

RMS amplitude

root mean squared amplitude represents an average amplitude value

energy

in sound, greater amplitude means greater energy in the waveform

loudness

how loud or soft a sound seems. relates to amplitude

ambient pressure

the normal/background pressure of the enviornment

periodic sound

a sound whose cycles repeat itself regularly

aperiodic sound

a sound where one cycle has no predictable relationship to the next cycle

quasi periodic sound

sound that is almost periodic but has small variations between cycle

attenuation

reduction in sound ampltiude/intensity; sound become weaker

inverse square law

as distance from a sound source increases, sound intensity decreases

absorption

when an obstacle/ material takes in sound energy

reflection

when sound bounces off an obstacle

Diffraction

when sound bends/spreads around an obstacle

complex processing

using both (up + down) processes at the same time and using the physical properties of sound to help us understand what we were hearing

brownian motion

sound makes changes and propagates leading to how it is heard

sound energy

transfer of energy from a vibratory source to a medium which propagates through the medium and then creates local density changes

Unbounded medium

a medium that contains no obstacles or conditions to affect sound wave propagation or alter the characteristics of the sound wave in any way