SHH 382: Exam 5

Central Auditory System

cochlear nerve, ascending auditory pathway, auditory cortex

Cochlear nerve synonyms

acoustic nerve, auditory nerve

Vestibular nerve

transmits vestibular impulses from the vestibular system

Cochlear nerve

transmits auditory impulses from the cochlea

Vestibulocochlear nerve

entirely sensory and has two parts, vestibular nerve and cochlear nerve

Ascending auditory pathway

connection between the cochlea and the auditory cortex

Ascending

sensory; traveling from the periphery (ear) to the central nervous system (auditory cortex)

Ascending auditory pathway anatomy

cochlea → 3 brainstem nuclei → thalamus → primary auditory cortex

Cochlear nuclei

located in the medulla oblongata. receives coded sound from the cochlea, first brain structure of the central auditory pathway

Superior olivary complex

located in the pons, analyzes intensity and time of arrival differences between the ears

Inferior colliculus

located in the midbrain, vertical and horizontal sound localization, generates acoustic startle response

Medial geniculate nucleus

located in thalamus, relay point between the brainstem nuclei and the auditory cortex

Auditory cortex

areas of auditory reception and perception in the temporal lobes of both hemispheres, superior temporal gyrus (Heschl’s gyrus)

Auditory cortex tonotopic arrangement

orderly representation of frequency created in the cochlea is preserved all the way to the auditory cortex

Dichotic listening

psychological test used to study left-hemispheric dominance for speech processing

Proprioception

sense of awareness of where our different body parts are

Vestibular

sense of balance

Illusions

sensory misinterpretations that are not resolved even with additional input

Auditory illusions

sensory misinterpretations in the auditory sphere

McGurk effect

an auditory-visual illusion where the sound you hear is influenced by what you see

The Shepard tone

three sine waves (high, middle and low-pitched) layered on top of each other and separated by octaves

Psychophysics

branch of psychology that studies the relationship between the physical world (physical stimuli) and the psychological world

Psychological world

the world as created by our minds based on sensory input and past experiences

Percept

mental representation of a phenomenon perceived in the real world

Physical sound dimension

duration, frequency, amplitude

Percepts

fast/slow, pitch, loudness

Threshold of hearing

a.k.a. absolute threshold; the dividing line between hearing an not hearing

Phon

unit of perceived loudness (subjective loudness)

Reference frequency

1,000 Hz (comparison point)

Equal loudness contours

shows the amount of sound pressure required for a frequency to be perceived: lower the line = less pressure/intensity to generate the perception

Speech banana

the area where most sounds of average conversational speech occur

Difference limen

the amount by which one stimulus must be different from another for a person to notice that the two stimulus are different

Precise limen difference

the difference at which the listener detects the sounds are different 50% of the time

Just noticeable difference

the difference by which the listener detects the sounds are different 100% of the time

Psychoacoustics

subfield of psychophysics, studies the mental representation generated from nerve impulses that represent the acoustic input