Lecture 2 Definitions: Perception Psychophysics and Psychoacoustics

psychophysics

study of the relation between the physical stimulus and the psychological (subjective) sensation

detection

determining the minimum amount of a particular stimulus that’s required for the individual to say that a stimulus is present

absolute threshold

the stimulus energy above which the stimulus is detectable

sensitivity

value of the ease an observer can tell the difference between the presence and absence of a stimulus or the difference between two

criterion

an internal threshold that is set by the observer

discriminability

how well an observer can separate the presence of a signal from its absence

just-noticeable difference (JND)

the smallest detectable difference between 2 stimuli, or the minimum change that can be correctly judged as different from a reference stimulus (the difference threshold)

weber’s law

the smallest change in a stimulus that can be detected is a constant proportion of the stimulus level

sine wave

the waveform for which variation as a function of time is a sine function

wavelength

time required for once cycle of a repeating waveform

frequency

number of times per unit that a pattern of pressure change repeats

amplitude/intensity

the magnitude of displacement (increase/decrease) of a sound pressure wave

hertz (Hz)

unit of measurement for frequency

decibel (dB)

a unit of measure for the physical intensity of sound

stereocilia

hairlike extensions on the tips of hair cells in the cochlea that initiate the release of NT

tip links

tiny filaments on the tip of each stereocilia where it is connected to the side of its neighbour

fourier analysis

a mathematical procedure by which any signal can be separated into component sine waves at different frequencies

fundamental frequency

the lowest-frequency component of a complex period sound

harmonic spectrum

the spectrum of a complex sound in energy is an integer multiple of the fundamental frequency

loudness

the psychological aspect of sound related to perceived intensity/amplitude

pitch

the psychological aspect of sound related mainly to the fundamental frequency

timbre

the psychological sensation by which a listener can judge that two sounds with the same loudness and pitch are dissimilar

psychoacoustics

branch of psychophysics in which the psychological correlates of the physical dimensions of sound are studied

audibility threshold

the lowest sound pressure level that can be reliably detected at a given frequency

equal-loudness curve

a graph plotting sound pressure level (dB SPL) against the frequency for which a listener perceives constant loudness

transduction

the conversion of a physical stimulus, such as light or sound, into a neural response through the activity of sensory receptors

interoception

the sense(s) of the internal state of the body

method of limits

a psychophysical method in which the particular dimension of a stimulus, or the difference between two stimuli, is varied incrementally until the participant responds differently

method adjustment

a method of limits in which the participant controls the change in the stimulus

fechner’s law

the magnitude of subjective sensation increases proportionally to the logarithm of the stimulus intensity

magnitude estimation

a psychophysical method in which the participant assigns values according to perceived magnitudes of stimuli

steven’s power law

principle describing the relationship between stimulus and resulting sensation that says the magnitude of subjective sensation is proportional to the stimulus magnitude raised to an exponent

signal detection theory

a psychophysical theory that quantifies the response of an observer to the presentation of a signal in the presence of noise. measures obtained from a series of presentations are sensitivity and criterion of the observer

receiver operating characteristic (ROC) curve

in signal detection, the graphical plot of the hit rate as a function of the false-alarm rate

bloch’s law

the detection threshold for a brief flash of light is the product of the luminance of the light and its duration

stimulus onset asynchrony (SOA)

the time between the onset of a stimulus and the onset of another

harmonic spectra

the spectrum of a complex sound in which energy is at integer multiples of the fundamental frequency

acoustic reflex

a reflex that protects the ear from intense sounds via contraction of the stapedius and tensor tympani muscles

volley principle

idea that multiple neurons can provide a temporal code for frequency if each neuron fires at a distinct point in the sound wave but does not fire on every period (e.g., early gun reloading formations)

tonotopic organization

an arrangement in which neurons that respond to different frequencies are organized anatomically in order of frequency

temporal integration

the process by which a sound at a constant level is perceived as being louder when it is of greater duration

conductive hearing loss

hearing loss caused by problems with the bone in the middle ear

otitis media

inflammation of the middle ear, common in children as a result of infection

otosclerosis

conductive loss caused by abnormal growth of the middle ear bones, most typically around the oval window next to the stapes

sensorineural hearing loss

most common and most serious form of auditory impairment; commonly occurs inside the cochlea and sometimes is the result to the AN

neural loss

actual loss of AN fibres, usually from aging

metabolic hearing loss

hearing loss caused by degraded ability of the stria vascularis to provide sufficient nutrients and ions to the cochlear partition

prescbycusis

age related hearing loss

hidden hearing loss

recently described disorder associated with loss of synapses between hair cells and AN fibers, disrupting connectivity to the brain