CSD 303 Part One

Amplitude

Amplitude

the maximum displacement of the particles of a medium (from equilibrium)- indicates the energy/intensity of a sound

Aperiodicity

a sound disturbance in which the wave shape does not repeat itself as a function of time (ex. static on the radio, a sudden explosion)

Audiometric Zero (0 dB HL)

average human threshold at each individual frequency tested

Complex Sounds

energy distributed at more than one frequency

Compression (Condensation)

particles in a medium being pushed closer towards each other

Cycling

time concept referring to movement of a vibrating object from rest position to maximum displacement in one direction

Damping

rate at which the magnitude of vibration and the loudness of the resultant sound decreases

Decibel (dB)

the most common unit used to measure loudness/sound intensity

Elasticity

the ability of an object or material to resume its normal shape after being stretched or compressed; stretchiness/springiness

Fourier Analysis

takes information from the time domain (waveform) and transforms it into the frequency domain (spectrum)

Frequency

the number of complete cycles that occur during a certain time period, usually 1 second

Fundamental Frequency

whole number multiple of of the component with the lowest frequency

Harmonics

whole number multiples of the fundamental frequency

Inertia

The tendency of an object to resist a change in motion

Mass

any form of matter

Noise

sounds that lack cyclical or repetitive vibrations, an unwanted sound

Peak Amplitude

linear measurement of a wave from the baseline to the point of maximum displacement

Peak-to-peak Amplitude

linear measurement of the distance from point of positive maximum displacement to negative maximum displacement

Period

the time (expressed in milliseconds) that it takes for a vibrating object to complete one cycle of vibration

Periodicity

a periodic sound disturbance in which the wave shape repeats itself as a function of time (ex. simple harmonic motion, tuning fork, pendulum)

Phase

the point in the cycle at which the vibrating object is located at a given moment in time

Pitch

perceptual correlate of frequency

Pure Tone

a sound that has almost all its energy located in a single frequency

Rarefraction

when particles are spread apart more than they normally would be

Reflection

sound that is reflected from any surface

Reverberation

multiple or continuous reflections of sound that prolong the existence of the sound within a confined space

Sinusoidal Motion (Simple Harmonic Motion)

a disturbance in a medium that occurs when devices such as tuning forks are activated and undergo simple "to and fro" motion.

Sound

a condition of disturbance of particles in a medium

Sound Pressure Level (SPL)

scale that measures amplitude in dynes/cm^2 or pascals- measurement is expressed in decibels

Spectrum

when amplitude is plotted as a function of frequency

Spring Mass Model

visual model that shows the properties of molecular elasticity

Transduction

change in the form of energy

Wave Form

graph that displays variations in pressure in relation to amplitude and time

Wavelength

linear measurement that refers to the distnace that a sound wave disturbance can travel during one complete cycle of vibration

Describe the motion of a sine wave

Describe spatial and temporal concepts associated with sine waves

Describe the relationship between frequency/period

period and frequency are inversely related to each other - period can be measured directly so we must know that in order to find frequency

Describe the difference between simple and complex sounds and provide examples

simple: all energy is located in a single frequency (ex. a tuning fork) complex: has energy distributed at more than one frequency (ex. speech sounds)

Differentiate periodicity and aperiodicity in sounds

periodicity: the wave shape repeats itself as a function of time aperiodicity: the wave shape does not repeat itself as a function of time

Define fundamental frequency and harmonics of complex sounds

fundamental frequency: whole number multiple of the component with the lowest frequency (the first bar, the lowest) harmonics: whole number multiples of fundamental frequency (all the bars above the lowest)

Describe the importance of the decibel, how it is computed, and how it is used in describing the energy of sound

the decibel helps to compare the intensities of different sounds; computed by taking the base-10 logarithm of the ratio

Frequency and Pitch are directly correlated

the higher the frequency, the higher the pitch

Audiogram

graph or table showing thresholds in hearing level at different frequencies

Audiometric Zero

level of pure tone signal that is just detectable by listeners with normal hearing

Azimuth

angle of incidence of a sound wave as it reaches the head

Bone Conduction

transmission of sound waves to the inner ear through vibration of the bones of the skull

Head Shadow Effect

reduction of sound level at the ear farther away from the sound source, caused by the presence of the head between the sound source and the ear. it is a factor in sound localization

Incident Sound

Sound coming directly from the source

Interaural Intensity Differences

localization cue described as the difference in intensity of a sound at the two ears; usually caused by the head shadow effect- also known as interaural level difference

Interaural Time Differences

localization cue described as the difference between time of arrival and of sound at one ear compared to the opposite ear- also known as interaural phase difference

Minimum Audible Field (MAF)

lowest level of sound heard when meausring auditory sensitivty through speakers

Minimum Audible Pressure (MAP)

lowest level of sound heard when measuring auditory sensitivity through earphones

Reflected Sound

sound that is reflected from any surface

Temporal Integration (Summation)

a change in threshold as the duration of a stimulus changes

Two-Alternative Force-Choice Procedure

psychological test measuring the limits of a client's threshold by presenting sound levels in a random order and asking the client to indicate whether or not the auditory stimulus was present in a given time period

Identify the primary cues used in auditory localization

Describe the differences between hearing by air conduction, and hearing by bone conduction

Hearing by air conduction is when sound travels through the outer, middle, and inner ear. Hearing by bone conduction is sound that travels through the head

Binaural

refers to both ears- opposite of monaural

Interaural Time Difference

the law that describes the loss of sound presure level as distance from theh sound source inscreases

Inverse Square Law

law that describes the loss of sound pressure level as distnace from the soudn source increases

Lateralization

effect of detecting a sound with a greater intensity in one ear relative to the other ear- if the sound intensity changes in one ear, the listener will perceive the sound source as moving

Localization

ability to identify the direction of a sound source

Simple Harmonic Motion

distubrance in a medium in which particles are displaced perpendicular to the direction of the disturbance

Sine Wave

temporal picture of cyclical variation - also called sine wave

Intensity

the power of a sound- relates to loudness

Constructive and Deconstructive Interference Sound

two traveling waves which exist in the same medium will interfere with each other- if their amplitudes add they are constructive, if their amplitudes are out of phase and subtract, they are deconstructive

Head Shadow

region of reduced amplitude of a sound because it is obstructed by the head.

Direct Sound

sound that travels directly from source to the receiver

dB IL dB SPL dB HL dB SL

dB IL

decibel intensity level scale

dB SPL

decibel sound pressure level

Describe the relationship between frequency/wavelength

wavelengths are determined when dividing speed (s) by frequency (f)