audition Flashcards
what are sound waves?
waves of pressure changes in air caused by the vibrations of a source
what is a sound cycle?
in a sound wave, a repeating segment of air changes
what physical property perceptually correlates to pitch?
frequency
how is pitch/frequency measured?
hertz
what physical property perceptually correlates to loudness?
amplitude
how is amplitude/loudness measured?
decibels
what physical property perceptually correlates to timbre?
waveform
can you measure waveform/timbre?
no
what is the young human adult sound detection range?
about 20 - 20,000 hertz
how does the amplitude threshold differ between loud and soft sounds?
the loudest sounds a human can hear are 1 million times the amplitude of the softest sounds
what is amplitude?
difference between the maximum and minimum sound pressure in a sound wave
what is loudness?
perceptual dimension of sound that is related to the physical dimension of amplitude; how loud or quiet a sound SEEM
what is decibels?
physical unit used to measure sound amplitutde, logarithmically related to sound pressure measured in micropascals
what is the absolute threshold mean?
the intensity of the least intense sound that can be heard
when is auditory sensitivity maximal?
in middle range, which is the range of frequencies present in most human speech sounds
what is pure tone?
sound wave in which air pressure changes over time according to a mathematical formula called a sine wave or sinusoid
what is hertz?
number of cycles per second of a sound wave
what is fourier show?
that waveforms of most periodic sounds have a more complex shape than a sine wave
what is harmonic?/
compotent frequency of a complex waveform that is an integer multiple of the fundamental frequency
what is timbre?
difference in sound quality between two sounds with same pitch and loudess
what is the illusion of the missing fundemental?
shows that the auditory system uses patterns of frequencies in a sounds harmonics as part of pitch perception
what is manner of onset and offset?
manner of onset (attack) and manner of offset (decay) also affect timbre perceptuon
how does the structure of the ear help in sound processing?
structure transduces sound into neural signals that are sent to the brain
what are the three parts of the brain?
outer, middle, inner
what is the pinna?
outermost portion of the ear, shape can modify incoming sound and contribute to localisation
what is the auditory canal?
narrow channel that funnels sound waves gathered by the
pinna onto the tympanic membrane and that amplifies certain frequencies in
those waves and contributes to high sensitivity to those frequencies
what is the tympanic membrane (eardrum)
thin, elastic diaphragm at the inner
end of the auditory canal that vibrates in response to the sound waves that
strike it; it forms an airtight seal between the outer ear and the middle ear
what are the ossicles?
three small bones (the malleus, incus, and stapes) in the
middle ear that transmit sound energy from the tympanic
membrane to the inner ear
what is the malleus? (hammer)
small bone in the inner ear; one of the
ossicles; transmits sound energy from the tympanic membrane to
the incus
what is the incus (anvil)?
small bone in the inner ear; one of the ossicles;
transmits sound energy from the malleus to the stap
what is the stapes? (stirrup)
transmits sound energy from the incus to the oval window
what is the oval window?
membrane-covered opening at the base of the
cochlea; vibrations of the membrane transmit sound energy from
the ossicles into the cochlea
what are the two characteristics of ear anatomy that help compensate for loss of sound energy?
- larger size of tympanic membrane concentrates sound
energy in much smaller area and effectively amplifies its
effect. - physical arrangement of ossicles produces a lever action
that magnifies vibrations of tympanic membrane.
what is the eustachian tube?
tube connecting the middle ear and the top part of the
throat
- is normally closed but can be briefly opened to equalize the air pressure in the middle ear with
the air pressure outside
what is the cochlea?
fluid filled compartment, coiled like a snail’s shell, within the temporal bone of the skull.
what do the inner hair cells do?
convey almost all information about sound
waves to the brain (afferent fibres)
what do outer hair cells do?
recieve information from the brain (using
efferent fibers). They are involved in an elaborate feedback
system
what is frequency represented by in the auditory system?
place and temporal code
what is frequency theory (temporal code)
suggests that the neurons’ firing rate matches the cycles per
second (Hz) - works only on lower frequency
what is place code?
tuning of different parts of the cochlea to different
frequencies
what is the frequency tuning of auditory nerve fibres accounted for by?
the frequency tuning of the
basilar membrane, a purely
mechanical factor
why is place code beneficial?
provides relatively better frequency representation of high frequency sounds than of low-frequency sounds
what is temporal code based on?
on a match between the frequencies in incoming
sound waves and the firing rates of Type I auditory nerve fiber
what frequencies can temporal code represent?
up to 5000 Hz
what is place code based on?
mechanical properties of Basilar membrane and supported by location of auditory nerve fibers by Frequency sensitivity
what frequencies can place coding represent?
above 5000 Hz
what is the cochlear nucleus?
the first brain stem nucleus at which afferent
auditory nerve fibers synapse.
what is the superior olive?
an early brain stem region in the auditory
pathway where inputs from both ears converge.
what is the inferior colliculus?
midbrain nucleus in the auditory pathway
what is the medial geniculate nucleus?
part of the thalamus that relays auditory signals to the temporal cortex and receives input from
the auditory cortex
what is the basic structure of the mammalian auditory system?
- cochlear nucleus
- superior olive
- inferior colliculus
- medial geniculate nucleus
what are the external components of the cochlear implant?
consist of a microphone, sound processor, and transmitter which essentially performs a Fourier analysis on external sounds
what are the internal components of the cochlear implant?
consist of a receiver–stimulator and an electrode system that
spirals around the cochlea and stimulates auditory nerve fibers,
using both place coding and temporal coding
what are the three steps in fourier’s process?
fourier analysis
fourier spectrum
fundemental frequency
