Audition Flashcards
Amplitude
Intensity of a sound wave
Sounds of greater amplitude seem louder
Frequency
Number of compressions per second (Hertz)
Pitch
Related aspect of perception
Higher frequency = higher pitch
Registered/coded in cochlea
Timbre
Tone quality or tone complexity
Prosody
People communicate emotion by alterations in pitch, loudness, and timbre
Outer Ear Structures
Pinna
Pinna
Familiar structure of flesh and cartilage attached to each side of head
Alters reflections of sounds waves to locate source of sound
Sound waves pass through auditory canal
Middle Ear Structures
Tympanic membrane
Oval window
Hammer, anvil, stirrup
Eustachian tube
Tympanic Membrane
Eardrum
Sound waves reach middle ear and vibrate tympanic membrane
Connects to three tiny bones that transmit the vibrations to the oval window
Oval Window
Membrane of the inner ear
Smallest bones in the body
Hammer, anvil, and stirrup OR malleus, incus, and stapes
Vibrations of tympanic membrane amplify to more forceful vibrations of smaller stirrup
Net effect converts sound waves into greater pressure on small oval window
Stirrup vibrates oval window which sets into motion fluid in cochlea (induces pressure in cochlea)
Eustachian Tube
Continuous fluid filled tube
Inner Ear Structures
Cochlea
Round Window
Hair cells
Vestibular canal
Tympanic canal
Cochlear duct
Organ of corti
Cochlea
Snail shaped structure of inner ear
Vibrations in fluid of the cochlea displace hair cells, thus opening ion channels in its membrane
Hair Cells
Between cochlea basilar membrane on one side and tectorial membrane on other
Stimulate cells of the auditory nerve, part of the 8th cranial nerve
Round Window
Regulates pressure in cochlea (through movement)
Vestibular Canal
Scala Vestibuli
Contains perilymph
Tympanic Canal
Scala timpani
Contains perilymph (share fluid body with vestibular)
Cochlear Duct
Scala Media
Contains endolymph
Regulates cells which produce neurotransmitter
Organ of Corti
Outer hair cells which terminate in cilia
Topped by tectorial membrane
Nerve fibres along base of membrane
Place Theory
High frequency sounds
Each area along membrane tuned to specific frequency
Each frequency activates hair cells at one place along membrane
Nervous system distinguishes frequencies based on which neurons respond
Drawback: basilar membrane bound too tight together for each part of resonate individually
Frequency/Timing Theory
Low frequency sounds
Entire basilar membrane vibrate with sound
Pitch is coded by firing rate of spiral ganglion cells
Action potentials are phase locked to sound frequency
Drawback: refractory period of neuron is too slow for this to happen for high frequency
Volley Theory
Middle frequency sounds
Auditory nerve produces volleys of impulses for sounds
Each wave of frequency excites at least a few neurons
Similarity between auditory and visual pathways
Both have ‘what’ and ‘where’ pathways
Essential for visual/auditory imagery
Need normal experiences to develop
Methods of Sound Localization
Interaural level difference
Interaural time difference
Phase differences between ears