PSYCH 1XX3 - Audition

sound wave

a longitudinal wave that is caused by vibrations and that travels through a medium

What happens to the ear drum if there is more dense air?

it is pushed outwards

What happens to the ear drum if there is less dense air?

it is pushed inwards

what are the three psychological properties of sinusoidal sound waves?

loudness, pitch and timbre

loudness

a variation in the amplitude, measured in decibels

what is the dB of a typical conversation?

60 dB

what is the dB of a concert?

120 dB

what is the dB of a whispering conversation?

27 dB

pitch

variation of frequency, inverse of wavelength, measured in Hz

timbre

variation of purity, describes the complexity of a sound

what are the three main portions of the ear?

external ear, middle ear and internal ear

what is the external ear composed of?

pinna, ear canal and ear drum

function of the pinna

collects sound waves in the environment and directs them into the ear canal

function of the ear canal

concentrates sound waves to hit the ear drum

function of the ear drum

vibrates at the frequency of the incoming sound waves and creates the back wall of the ear canal

what is the middle ear made up of?

hammer (malleus), anvil (incus) and stirrup (stapes)

what is the function of the auditory ossicles?

amplify sound

what is the inner ear composed of?

cochlea, oval window, round window, basilar membrane and hair cells

function of the cochlea

contains neural tissue to transfer the changes in neural fluid movement into neural signals

function of the oval window

attached to the ossicles, when it moves it displaces the fluid in the cochlea and increases pressure

location of the round window

located on the opposite side of the basilar membrane to the window

basilar membrane

A structure that runs the length of the cochlea in the inner ear and holds the auditory receptors, called hair cells.

low frequency sounds

displaces the basilar membrane at the apex, further from the oval window

high frequency sounds

displaces the basilar membrane further from the apex, closer to the oval window

hair cells

receptors that translate physical sound into neural impulses

outer hair cells

more numerous, fewer connections with the brain and are unmyelinated

outer hair cells function

amplify sound

inner hair cells

less numerous, more connections to the brain and are myelinated

inner hair cells function

send pitch information

transmission of a neural signal from the cochlea

-Neurotransmitter triggers EPSPs in the cochlear nerve fibres

- The cochlear nerve fibres send the signal to the cochlear nucleus in the hindbrain

what are the two streams of the cochlear nucleus?

dorsal stream and ventral stream

how is audition organized in the brain?

tonotopic organization

what are the two interaural cues used in auditory localization?

timing of incoming sound between ears and intensity difference between ears

sound shadow

occurs for distant sounds, diminishes the intensity of sound at the ear distal to where the sound came from

superior olivary complex

compares sound inputs from each ear

What is the challenge with sounds coming from directly in front or behind us?

Sounds in front and behind us are hard to localize, because they have the same timing and intensity

pinna cues

Help localize the elevation of a sound source

- When altered -> dramatic effect on localization ability

echolocation

process by which a receiver emits sound pulses and analyzes the returning echo to form a perceptual image of objects in the environment

co-evolution

the process by which the evolution and adaptation of one species can directly affect the evolution of traits in another species

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