Chapter 11 Flashcards
Acoustic prism
The way the cochlea separates frequencies entering the ear to create activity at different places along the basilar membrane.
Amplitude
In the case of a repeating sound wave, such as the sine wave of a pure tone, amplitude represents the pressure difference between atmospheric pressure and the maximum pressure of the wave.
Apex of the cochlea
The end of the cochlea farthest from the middle ear.
Attack
The buildup of sound energy that occurs at the beginning of a tone.
Audibility curve
A curve that indicates the sound pressure level (SPL) at threshold for frequencies across the audible spectrum.
Auditory canal
The canal through which air vibrations travel from the environment to the tympanic membrane.
Auditory response area
The psychophysically measured area that defines the frequencies and sound pressure levels over which hearing functions. This area extends between the audibility curve and the curve for the threshold of feeling.
Base of the cochlea
The part of the cochlea nearest the middle ear.
Basilar membrane
A membrane that stretches the length of the cochlea and controls the vibration of the cochlear partition.
Characteristic frequency
The frequency at which a neuron in the auditory system has its lowest threshold.
Cilia
Fine hairs that protrude from the inner and outer hair cells of the auditory system. Bending the cilia of the inner hair cells leads to transduction.
Cochlea
The snail-shaped, liquid-filled structure that contains the structures of the inner ear, the most important of which are the basilar membrane, the tectorial membrane, and the hair cells.
Cochlear amplifier
Expansion and contraction of the outer hair cells in response to sound sharpens the movement of the basilar membrane to specific frequencies. This amplifying effect plays an important role in determining the frequency selectivity of auditory nerve fibers.
Cochlear implant
A device in which electrodes are inserted into the cochlea to create hearing by electrically stimulating the auditory nerve fibers. This device is used to restore hearing in people who have lost their hearing because of damaged hair cells.
Cochlear partition
A partition in the cochlea, extending almost its full length, that separates the scala tympani and the scala vestibuli. The organ of Corti, which contains the hair cells, is part of the cochlear partition.
Decay
The decrease in the sound signal that occurs at the end of a tone.
Decibel (dB)
A unit that indicates the pressure of a sound stimulus relative to a reference pressure: dB=20 log (p/po) where p is the pressure of the tone and po is the reference pressure.
Eardrum
Another term for the tympanic membrane, the membrane located at the end of the auditory canal that vibrates in response to pressure changes. This vibration is transmitted to the bones of the middle ear.
Effect of the missing fundamental
Removing the fundamental frequency and other lower harmonies from a musical tone does not change the tone’s pitch. See also periodicity pitch.
Equal loudness curve
A curve that indicates the sound pressure levels that result in a perception of the same loudness at frequencies across the audible spectrum.
First harmonic
A pure tone with frequency equal to the fundamental frequency of a complex tone. See also fundamental frequency.
Frequency
The number of times per second that pressure changes of a sound stimulus repeat. Frequency is measured in Hertz, where 1 Hertz is one cycle per second.
Frequency spectrum
A plot that indicates the amplitudes of the various harmonics that make up a complex tone. Each harmonic is indicated by a line that is positioned along the frequency axis, with the height of the line indicating the amplitude of the harmonic.
Frequency tuning curve
Curve relating frequency and the threshold intensity for activating an auditory neuron.
Fundamental
A pure tone with frequency equal to the fundamental frequency of a complex tone. See also fundamental frequency.
Fundamental frequency
The fi rst harmonic of a complex tone; usually the lowest frequency in the frequency spectrum of a complex tone. The tone’s other components, called higher harmonics, have frequencies that are multiples of the fundamental frequency.
Hair cell
Neuron in the cochlea that contains small hairs, or cilia, that are displaced by vibration of the basilar membrane and fluids inside the inner ear. There are two kinds of hair cells: inner and outer.
Harmonics
Pure-tone components of a complex tone that have frequencies that are multiples of the fundamental frequency.