Psyc 367 (UAlberta- Farley) Ch. 11 Hearing

Amplitude Modulation

Adjusting the level (or intensity) of a sound stimulus so it fluctuates up and down.

Amplitude

the pressure difference between atmospheric pressure and the maximum pressure of the wave.

difference in pressure between high + low peaks of wave

loudness

Aperiodic Sounds

Sound waves that do not repeat.

Apex

The end of the cochlea farthest from the middle ear.

Attack of tones

The buildup of sound energy that occurs at the beginning of a tone.

Audibility Curve

A curve that indicates the sound pressure level (SPL) at threshold for frequencies across the audible spectrum.

Audiogram

Plot for hearing loss vs frequency.

Auditory Receiving Area (A1)

The area of the cortex, located in the temporal lobe, that is primary receiving for hearing.

Auditory Response Area

The psychophysically measured area that defines the frequencies and sound pressure levels over which hearing functions.

This area extends between the audibility curve and the curve for the threshold of feeling (causes pain).

Base

(of the cochlea) The end of the cochlea nearest the middle ear.

Basilar Membrane

A membrane that stretches the length of the cochlea partition.

vibrates in response to sound + supports the organ of corti

up-down motion from vibrations inside cochlea liquid

Belt Area

Auditory area in the temporal lobe that receives signals from the core area and sends signals to the parabelt area.

Characteristic Frequency

The frequency at which a neuron in the auditory system has its lowest threshold/most sensitive

Cilia

Fine hairs that protrude from the inner and outer hair cells of the auditory system.

• capture sound vibrations and send them to the brain as electrical impulses through the auditory nerve.

• motion sensors to monitor fluid in the ear and help the brain maintain balance

• move earwax through the ear to keep the ear canal open

Cochlea

The snail-shaped, liquid-filled structure that contains the structures of the inner ear,

• the basilar membrane, tectorial membrane, and the hair cells.

location which transduction of pressure waves occurs

Cochlear Amplifier

Expansion and contraction of the outer hair cells in response to sound sharpens the movement of the basilar membrane to specific frequencies.

This amplifying effect plays an important role in determining the frequency selectively of auditory nerve fibres.

Cochlear Nucleus

The nucleus where nerve fibres from the cochlea first synapse.

Cochlear partition

A paritition in the cochlea, that separates the scala tympani (lower half) + scala vestibuli (upper half)

The Organ of Corti, which contains the hair cells, is part of it.

Core Area

The area in the temporal lobe that includes the primary auditory cortex (A1) and some nearby areas.

Signals from the core area are transmitted to the belt area of the auditory cortex.

Decay of tones

The decrease in the sound signal that occurs at the end of a tone.

Decibel (dB)

A unit that indicates the pressure of a sound stimulus relative to a reference pressure.

measure of loudness

Effect of the Missing Fundamental frequency

Removing of the fundamental frequency and other lower harmonies from a musical tone does not change the tone's pitch.

when your brain hears a pitch that isn’t actually there. Even if the lowest sound frequency (fundamental frequency) is removed, your brain uses the higher-pitched tones (harmonics) to figure out what the pitch should be

Equal Loudness Curves

A curve that indicates the sound pressure levels that result in a perception of the same loudness at frequencies across the audible spectrum.

Frequency Spectrum

A plot that indicates the amplitudes of the various harmonics that make up a complex tone.

Each harmonic is indicated by a line that positioned along the frequency axis, with the height of the line indicating the amplitude of the harmonic.

Frequency Tuning Curve

Curve relating frequency and the threshold intensity for activating an auditory neuron.

Fundamental Frequency

The first harmonic of a complex tone; usually the lowest frequency in the frequency spectrum of a complex tone.

Fundamental

A pure tone with frequency equal to the fundamental frequency of a complex tone.

Hair Cells

Neurons in the cochlea that contain small hairs, or cilia, that are displaced by vibration of the basilar membrane, and fluids inside the inner ear.

Inner and outer are types.

Harmonic

Pure-tone components of a complex tone that have frequencies that are multiples of the fundamental frequency.

Hertz (Hz)

The unit for designating the frequency of a tone. One Hz equals one cycle per second.

Hidden Hearing Loss

Hearing loss that occurs at high sound levels, even though the person's thresholds, as indicated by the audiogram, are normal.

has difficultly perceiving more complex “real world” sounds

Higher Harmonics

Pure tones with frequencies that are whole number multiples of the fundamental frequency.

Ossicle: Incus (anvil)

The second of the three ossicles of the middle ear.

It transmits vibrations from the malleus to the stapes.

Inferior Colliculus

A nucles in the hearing system along the pathway from the coclea to the auditory cortex.

Receives inputs from the superior olivary nucleus.

signal integration, frequency recognition, and pitch discrimination

Inner Ear

The innermost division of the ear, containing the cochlea and the receptors for hearing.

Inner Hair Cells

Auditory receptor cells in the inner ear that are primarily responsible for auditory transduction and the perception of pitch.

Leisure Noise

Noise associated with leisure activities such as listening to music, hunting, and woodworking.

Exposure to high levels of leisure noise for extended periods can cause hearing loss.

Level

Short for sound pressure level or sound level. Indicates the dB or sound pressure of a sound stimulus.

Loudness

The quality of sound that ranges from soft to loud. For a tone of a particular frequency, loudness usually increases with increasing dBs.

Ossicle: Malleus(hammer)

The first of the ossicles in the middle ear.

moves due to/receives vibrations from the tympanic membrane and transmits these vibrations to the incus.

Middle Ear

The small air-filled space between the auditory canal and the cochlea that contains the ossicles.

Middle-Ear Muscles

Muscles attached to the ossicles in the middle ear.

The smallest skeletal muscles in the body

contract in response to very intense sounds and dampen the vibration of the ossicles: to protect the inner ear from potentially damaging stimuli

Noise

A sound stimulus that contains many random frequencies.

Noise-Induced Hearing Loss

A form of sensorineural hearing loss that occurs when loud noises cause degeneration of the hair cells.

Octave

Tones that have frequencies that are binary multiples of each other (2, 4, etc.). For example, an 800-Hz tone is one octave above a 400-Hz tone.

Organ of Corti

The major structure of the cochlear partition, containing inner + outer hair cells, the basilar membrane, the tectorial membrane, and the receptors for hearing.

Ossicles

Three small brones in the middle ear that transmit vibrations from the outer to the inner ear.

act to amplify the vibrations for better transmission to the fluid

Outer Ear

The pinna and auditory canal

protects the tympanic membrane (eardrum_ at the end of the canal

resonance occurs

Outer Hair Cells

Auditory receptor cells in the inner ear that amplify the response of inner hair cells by amplifying the vibration of the basilar membrane.

Oval Window

A small, membrane-covered hole in the cochlea that receives vibrations from the stapes.

Parabelt Area

Auditory area in the temporal lobe that receives signals from the belt area.

Periodic Sounds

A sound stimulus in which the pattern of pressure changes repeats.

Periodic Tone

A tone in which the waveform repeats.

Phase Locking

Firing of auditory neurons in synchrony with the phase of an auditory stimulus.

Pinna

The part of the ear that is visible on the outside of the head.

helps with sound

collects and channels sound waves into the ear canal

Pitch Neurons

A neuron that responds to stimuli associated with a specific pitch.

These neurons fire to the pitch of a complex tone regardless of what harmonic is heard

Pitch

The quality of sound, ranging from low to high, that is most closely associated with the frequency of a tone.

Place Theory of Hearing

The proposal that the frequency of a sound is indicated by the place along the Organ of Corti at which nerve firing is highest.

Modern place theory is based on Bekesy's traveling wave theory of hearing.

suggests that pitch perception is based on the relation between a sound’s frequency + place along the basilar membrane that’s activated

Presbycusis

A form of sensorineural hearing loss that occurs as a function of age, usually associated with a decrease in the ability to hear high frequencies.

males > females

can be casued by exposure to some drugs that damage the hair cells

related to exposure to environmental sounds, therefore also called sociocusis.

Primary Auditory Cortex (A1)

An area of the temporal lobe that receives signals via nerve fibres from the medial geniculate nucleus in the thalamus.

Pure Tone

A tone with the pressure changes that can be described by a single sine wave.

basic building block of sounds

a sound that consists of one single frequency

Resolved Harmonics

Harmonics in a complex tone that create separated peaks in basilar membrane vibration, and so can be distinguished from one another.

Usually lower harmonics of a complex tone.

lower harmonic are more useful for perceiving pitch

Resonance

A mechanism that enhances the intensity of certain frequencies because of the reflection of sound waves from the eardrum interact with sound waves entering the canal

auditory canal amplifies frequencies between about 1000 and 5000 Hz.

Resonant Frequency

The frequency that is most strongly enhances by resonance + most reinforced. Of a closed tube is determined by the length of the tube.

Sound Level

The pressure of a sound stimulus, expressed in dB.

Sound Pressure Level (SPL)

A designation used to indicate that the reference pressure used for calculating a tone's dB rating is set at 20 micropascals, near the threshold for most sensitive frequency range for hearing.

Sound Wave

Pattern of pressure changes in a medium. Most of the sounds we hear are due to pressure changes in the air, although sound can be transmitted through water and solids as well.

Ossicle: Stapes(stirrup)

The last of the three ossicles in the middle ear.

It receives vibrations from the incus and transmits these vibrations to the oval window of the inner ear.

Subcortical Structures

Structures below the cerebral cortex.

Superior Olivary Nucleus

A nucleus along the auditory pathway from the cochlea to the auditory cortex.

Receives input from the cochlear nucleus.

brain stem

plays a crucial role in auditory processing and sound localization

Tectorial Membrane

A membrane that stretches the length of the cochlea and is located directly over the hair cells.

Vibrations of the cochlar partition cause the membrane to bend the hair cells by rubbing against them.

back-forth motion from vibrations inside cochlea liquid

Temporal Coding

The connection between the frequency of a sound stimulus and the timing of the auditory nerve fibre firing.

Timbre

all other perceptual aspects of a sound besides loudness, pitch, and duration.

the quality of a sound produced by a voice or instrument

Tone Chroma

The perceptial similarity of notes separated by one or more octaves.

Tone Height

The increase in pitch that occurs as frequency is increased.

Tonotopic Map

An ordered map of frequencies created by the responding of neurons within structures in the auditory system.

Neurons at the apex respond best to low frequencies

neurons at the base respondi best to high frequencies.

Traveling Wave

In the auditory system, viration of the basilar membrane in which the peak of the vibration travels from the base of the membrane to its apex.

Tympanic Membrane (Eardrum)

A membrane at the end of the auditory canal that vibrates in response to vibrations of the air and transmits these vibrations to the ossicles in the middle ear.

Unresolved Harmonics

Harmonics of a complex tone that can't be distinguished from one another because they are not indicated by separate peaks in the basilar membrane vibration.

The higher harmonics of a tone are most likely to be unresolved.

physical definition of sound

pressure changes in the air or other medium

perceptual definition of sound

the experience we have when we hear

condensation (compression)

diaphragm of a speaker moves out, pushing air molecule together

A region of increased pressure on a sound wave

rarefaction (expansion)

diaphragm of a speaker moves in, pushing the air molecules apart

A region of decreased pressure on a sound wave

frequency

number of cycles within a given time period

measured in Hz

related to perception of pitch

periodic complex tones

consist of a number of pure tones (harmonics)

a sound wave that repeats in a pattern, but is made up of multiple sine waves with different frequencies

auditory canal/ear canal

a tube that carries sound from the outer ear to the eardrum in the middle ear

Middle ear assisting with amplifying the sound

1. concentrating the vibrations of the eardrum onto the much smaller stapes

2. being hinged; creating lever action = amplifies a small force

stereocilia

parts of the outer hair cells

bend in response to movement of organ of corti + tectorial membrane

tip links: movement in 1 direction opens ion channels

neural frequency tuning curves

produced by pure tones used to determine the threshold for specific frequencies measured at single neurons

anterior auditory cortex

plays a critical role in processing complex sounds, particularly in recognizing and interpreting what a sound is (its identity), as opposed to where it is coming from