5 - Auditory Perception Flashcards
Sound propagation
sound travelling to one place or another
particles oscillate back and forth about they do not propagate with the wave
speed of sound in air water and glass
air - 340 m/s
water - 1500 m/s
glass - 5300 m/s
sound waves have 2 basic features:
amplitude (loudness) - sound pressure level (dB SPL)
frequency (pitch) - number of cycles per second (Hertz Hz)
- sounds that consist of a sine wave are known as pure tones
what are most sounds we hear made of
one fundamental frequency
several harmonies of the fundamental
what is the fundamental
the musical pitch of a note that is perceived as the lowest
the human audible spectrum ranges from
20 to 20,000 Hz
sensitivity is greatest in the range of about 500 to 5000 Hz
why do smaller animals hear higher pitches
the cochlea is smaller and resonates better at higher frequencies
what is timber
when two tones have the same loudness, pitch and duration but sound different - sound is a difference in timber
what does the outer ear do
and two parts
gather sound
pinna
ear canal
what does the middle ear do and three parts
mechanical transformer
its air filled
tympanic membrane
ossicles (malleus - incus - stapes)
footplate connected to the oval window
what does the inner do and 3 parts
where auditory receptors are located
its fluid filled
semicircular canals
vestibule
cochlea
how do we capture sounds
the middle ear transfers the force from the tympanic membrane to the oval window through the ossicles
what is tonotopic mapping
sounds of diff frequency result in maximal displacement at different points along the membrane
inner ears receptor organ
organ of Corti
contains some 16000 hair cells arrayed in 4 rows
cochlear implant
mic receiving sound signals from the environment
sound processor that divides complex sounds in frequency bands
transmitter that send sound signals
array of 22 electrodes implanted along the cochlea`
binaural cues
used by both ears for azimuth localization
monoaural cues
used by one ear for elevation localization
LSO
lateral superior olive
MNTB
medial nucleus of the trapezoid body
tonotopic organisation
the nerve fibres are spatialy arranged to correspond to their basilar membrane origin
WHAT pathway
monaural
focuses mainly on identifying and classifying different types of sounds
WHERE pathway
binaural
involves in the localisation of a sound stimlulus
3 main auditory areas in the monkey cortex
the core area which conations the primary auditory receiving area (A1)
the Belt area
the Parabelt area
