Chapters 9, 10, 11, 13. WLU-PS262: Perception and Sensation

Amplitude

Magnitude of displacement (increased or decrease) of a pressure wave. LOUDNESS

Frequency

# of times per second that a pattern of pressure changes repeats. PITCH

Loudness

Psychological aspect of sound related to perceive intensity (amplitude). More intense= Louder `

Pitch

Psychological aspect of sound related to the fundamental frequency

Sine Wave

Wave form of which variation as a function of time is a sine-function

Spectrum

Rep of the relative energy (intensity) present at each frequency

Harmonic Spectrum

Complex sound in which energy is integrated multiples of the fundamental frequency.

Fundamental Frequency

Lowest-Frequency component of a complex periodic sound

Timbre

Psychological sensation by which a listener can judge that two sounds w/ the same loudness and pitch are different. Quality is conveyed by harmonics and other high frequency

Pinna

Outer, Funnel-like part of the ear

Ear Canal

Conducts sound vibrations from the pinna to the tympanic membrane and prevents damage to the tympanic membrane

Tympanic Membrane

Thin sheet of skin at the end of the outer ear canal. Vibrates in response to sound.

Outer Ear

External sound-gathering portion of the ear, consisting of the pinna and ear canal

Middle Ear

Air-filled chamber containing the ossicles. Conveys and amplifies vibrations from the eardrum to the oval window

Ossicle

3 tiny bones of the middle ear

Malleus

Most exterior of the 3. Receives Vibrations from the ear drum and attached to the incus`

Incus

Middle of the 3 connects them together

Stapes

Most interior of the 3. Pressed against oval window of the cochlea.

Oval Window

Flexible opening to the cochlea through which the stapes transmits vibrations to the fluid inside

Inner Ear

Hollow cavity in the temporal bone of the skull, and the structures within this cavity. Cochlea and the semicircular canals of the vestibular system

Tensor Tympani

Muscles attached to the malleus. Tensing the tensor tympani decreases vibration.

Stapedius

Muscle attached to the stapes. Tensing the stapedius decreased vibration

Acoustic Reflex

Reflex that protects the ear from intense sounds, Via contractions

Cochlea

Spiral structure of the inner ear containing the organ of Corti

Tympanic Canal

1/3 fluid-filed passages in the cochlea. Tympanic canal extends from the round window at the base fo the cochlea to the helicotrema at the apex

Vestibular Canal

1/3 extends from oval window at the base of the cochlea to the base of the cochlea to the helicotrema at the apex

Middle Canal

1/3 sandwiched between tympanic and vestibular canals at the apex of the cochlea

Helicotrema

Opening that connects the tympanic and vestibular canals at the apex of the cochlea

Reissner's membrane

A thin sheath of tissue separating the vestibular and middle canals in the cochlea

Basilar Membrane

a plate of fibres that form the base of the cochlear partition and separates the middle and tympanic canals in the cochlea

Cochlear Partition

Combined basilar membrane, Tectorial membrane and organ of Corti which are together responsible for the transduction of sound waves into neural signals

Round Window

Soft area of tissue at the base of the tympanic canal that releases excess pressure remaining from extremely intense sounds

Organ of Corti

Structure on the basilar membrane of the cochlea that is composed of hair cells and dendrites of auditory nerve fibres

Hair Cell

Any cell that has stereo cilia for transacting mechanical movement in the inner ear into neural activity. Sent to the brain

Auditory Nerve

Collection of neurons that convey info from hair cells to the cochlea

Stereocilium

Any of the hairlike extensions on the tips of the hair cells in the cochlea that when flexed initiate the release fo neurotransmitters. looks like a class photo or shaped like a V or W.

Tectorial Membrane

Gelatinous structure, attached on one end, that extends into the middle canal of the cochlea, floating above inner ear hair cells touching outer hair cells

Tip Link

A tinny filament that stretches from the tip of a stereocilium to the side of it's neighbour

Place Code

Tuning of different parts of the cochlea to different frequencies in which info about the particular frequency of an incoming sound wave is coded by the place along the cochlear partition that has the greatest mechanical displacement

Higher Frequencies

Affects the narrow, and stiffer regions closer to the base

Lower Frequencies

Causes displacement in the wider, more flexible regions, closer to the apex

Afferent Fiber

Neuron that carries sensory info to the central nervous system. 90% the TO

Efferent Fibers

Neuron that carries info to the CNS and to the Periphery. the FROM

Threshold Tuning

Graph Plotting the threshold of a neuron in response to sine waves w/ varying frequency at the lowest intensity that will give rise to a response

Characteristic Frequencies

Frequencies to which a particular auditory nerve fibre is most sensitive

Two-Tone Suppression

Decrease in the firing rate of one auditory nerve fibre due to one tone, when a second tone is presented at the same time.

Isointensity Curve

Map Plotting the firing rate of an auditory nerve fibre against varying frequencies at varying intensities

Rate Saturation

Point at which a nerve fibre is firing as rapidly as possible and further stimulation in incapable of of increasing firing rates.

Rate-Intensity Function

Graph plotting the firing rate of an auditory nerve fibre in response to a sound of constant frequencies at increasing intensities

Low-Spontaneous Fibre

Low Rate (less then 10 spikes per second) of spontaneous firing. Require relatively intense sounds before they fire at higher rates

High-Spontaneous Fibre

High are (10-30+ Spikes per second) Increasing their firing rate in reposes to relatively low levels of sound

Phrase Locking

Firing a single neuron at one distant point in the period (cycle) of a sound wave at a given frequency. Need not fire on EVERY cycle buy will occur at the same time

Temporal Code

Tuning of different parts of the cochlea to different frequencies in which info about a particular frequency of an incoming sound wave is coded by the timing of neural firing as it relates to the period of the sound

Volly Principle

Multiple neurons can provide a temporal code for frequencies if each neuron fires at a distant point in the period of a sound wave but doesnt fire on every period

Cochlear Nucleus

The first brain stem nucleus at which afferent auditory nerve fibres synapse

Superior Olive

Early brain stem region in the auditory pathway where inputs from both ears converge

Inferior Colliculus

Midbrian nucleus in the auditory pathway

Medical Geniculate Nucleus

Part of the thalamus that replay auditory signals to the temporal cortex and receives input from the auditory cortex

Tonootopic Organization

Arrangment in which neurons that respond differently frequencies are organized automatically in order of frequencies

Primary Auditory Cortex (A1)

First area within the temporal lobes of the brain responsible for processing acoustic info

Belt Area

Region of the cortex, Directly adjacent to the primary auditory cortex (A1) which inputs from A1 where neurones respond to more complex characteristics of sound

Psychoacoustics

Branch of psychophysics that studies the psychological correlates of the physical dimensions of acoustics in order to understand how the auditory system operates

Audibility Threshold

Lowest sound pressure level that can be reliably detected at a given frequencies

Equal-Loudness Curve

A graph plotting sound pressure level against the frequency for which a listener perceives consistent loudness

Temporal Intergration

Process by which a sound at a constant level is perceives as being louder when its of greater duration. the term also apply's to perceived brightness, which depends on the duration of light

Masking

Using a sound, freq noise, to make the detection of another sound more difficult

White Noise

All audible freq in equal amounts. Hearing in analogous to white light in vision, for all wavelengths are present

Critical Bandwidth

range of freq conveyed within a channel in the auditory system

Conductive Hearing Loss

Caused by problems with the bones of the middle ear

Otitis Media

Inflammation of mid ear commonly in children as a result of infection

Otosclerosis

Abnormal growth of the middle-ear bones causing infection

Sensorineural Hearing Loss

Due to defects in the Cochlea or auditory nerve

Interaural Time Difference (ITD)

The difference in time between arrivals of sound at one ear vs the other

Azimuth

The angle of a sound sources on the horizontal plane relative to a point in the centre of the head between the ears. Its measured in degrees with 0 degrees being straight ahead. the angel increases clockwise towards the right, with 180 degrees being directly behind

Medial Superior Olive (MSO)

A relay nation in the brain stem where inputs from both ears contribute to detection of the ITD

Interaural Level Difference (ILD)

The difference between levels (intensities) of sound at one ear vs the other

Lateral Superior Olive (LSO)

A relay station in the brain stem where inputs from both ears contribute to detection of the interaural level difference (ILD)

Cone of Confusion

A region of positions in space where two sounds produced the same time and level differences (ITD and ILD)

Directional Transfer Function (DTF)

Measure that describes how the pinna, ear canal, head and torso change the intensity of s sounds with different freq that arrive at each ear from different locations in space

Inverse-Square Law

A principle stating that as distance from a source increases, intensity decreases faster such that decrease in intensity is equal o the distance squared. This general law also applies to optics as other forms of energy

Fundamental Frequency

the lowest frequency component of a complex periodic sound

Timbre

Psychological sensations by which a listener can judge that two sounds with the same loudness and pitch are NOT similar. Timbre Qualitiy is converted by harmonies and other high freq

Attack

The part of a sound during which amplitude includes (onset)

Decay

The part of a sound during which amplitude decreases (offset)

Source segregation

Processing an auditory scene consisting of multi sound sources into operate sound images

Auditory Stem Segregation

The perceptual organization of a complex acoustic signal to separate auditory events for which each stream is heard as a separate event

Similarity

Gestalt grouping rule stating that the tendency of two sounds to group together will increase as the acoustic similarity between them increases

Common Fate

Gestalt grouping rule stating that the tendency of sounds to group together will increase if they being and or end the same time

Good Continuation

Gestalt grouping rule stating that sounds will tend to group together as continuous if they seem to share a common path, similar to a shared contour for vision

Acoustic Startle Reflex

The very rapid motor response to a sudden sound. very few neurons are involved in the basic startle reflex, which can also be affected by emotional state

Pitch

Psychological Aspect of sound related mainly to perceived frequency

Octave

Interval between two sound freq having a ratio of 2:1

Tone Height

Sound quality corresponding to the level of pitch. Tone height is monotonically related to frequency

Tone Chroma

A sound quality shared by tones that have the same octave interval

Chord

A combination of three of more musical notes with different pitches played simultaneously

Absolute Pitch (AP)

A rate ability whereby some people are able to very accurately name or produces notes without comparison to other notes

Melody

A sequence of notes of chords perceived as a single coherent structure

Tempo

The Perceived Speed of the prevention of sounds

Syncopation

Any Deviation from a regular rhythm

Vocal Tract

The airway above the Larynx used for the production of speech The vocal tract includes the oral race and nasal tract