Chapter 11 Flashcards
What are the two parts of sound?
- Physical stimulus
- Perceptual response (we are perceiving it)
What is a sound wave?
Pattern of pressure changes in a medium. Most of the sounds we hear are due to pressure changes in the air, although sound can be transmitted through water and solids as well.
What is a pure tone?
A tone with pressure changes that can be described by a single sine wave.
What is frequency?
the number of cycles per second that the pressure changes repeat
Pitch
HZ - 1 hz is one cycle per second
What is amplitude?
the size of the pressure change
Loudness
Decibel (DB) - pressure of a sound stimulus
What is the fundamental frequency of the tone?
The first 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.
What are the harmonics of a tone?
Complex tones are a number of pure tone (sine-wave) components added together
What is the fundamental of a tone?
pure tone with frequency equal to the fundamental frequency
What are Higher harmonics?
pure tones with frequencies that are whole-number (2, 3, 4, etc.) multiples of the fundamental frequency.
What are the two Perceptual Aspects of Sound?
- loudness, which involves differences in the perceived magnitude of a sound, illustrated by the difference between a whisper and a shout; and
- pitch, which involves differences in the low to high quality of sounds, illustrated by what we hear playing notes from left to right on a piano keyboard.
What does the audibility curve show?
indicates the threshold for hearing versus frequency, indicates that we can hear sounds between about 20 Hz and 20,000 Hz and that we are most sensitive (the threshold for hearing is lowest) at frequencies between 2,000 and 4,000 Hz
What is the auditory response area?
we can hear tones that fall within this area
What is tone height?
The increase in pitch that occurs as frequency is increased.
What is the effect of the missing fundamental?
Removing the fundamental frequency and other lower harmonies from a musical tone does not change the tone’s pitch.
What does timbre depend on (two ways)?
- attack (the buildup of sound at the beginning of the tone)
- tone’s decay (the decrease in sound at the end of the tone).
What is periodic sounds vs aperiodic sounds
Periodic: A sound stimulus in which the pattern of pressure changes repeats. (pure tones and musical instruments)
Aperiodic: Sound waves that do not repeat. (door slamming)
Name the parts of the outer ear:
- pinnae
-auditory canal
-tympanic membrane, or eardrum
(Also amplifies the sound -resonant frequency:The frequency that is most strongly enhanced by resonance)
Name the parts of the middle ear?
-ossicles: malleus, incus, and stapes
-oval window (stapes transmits vibrations to here)
-middle-ear muscles (Muscles attached to the ossicles in the middle ear - dampen the vibration of the ossicles)
How to ossicles solve the air to liquid problem?
- Increase the pressure (amplify sound)
- Uses a leaver to be able to lift more
What is the structure of the inner ear?
- cochlea
- cochlear partition (contains The organ of Corti, which contains the hair cells)
- basilar membrane (A membrane that stretches the length of the cochlea and controls the vibration of the cochlear partition)
- tectorial membrane (A membrane that stretches the length of the cochlea and is located directly over the hair cells. Vibrations of the cochlear partition cause the tectorial membrane to bend the hair cells by rubbing against them.)
What are stereocilia?
Little tips on top of hair cells that bend in response to pressure changes
What are the two results of the up-and-down motion of the basilar membrane
- it sets the organ of Corti into an up-and-down vibration, and
- it causes the tectorial membrane to move back and forth, as shown by the red arrow.
What are tip links?
Structures at the tops of the cilia of auditory hair cells, which stretch or slacken as the cilia move, causing ion channels to open or close.
What is phase locking?
Firing of auditory neurons in synchrony with the phase of an auditory stimulus
What does the basilar membrane do?
Moves like a travelling wave - In the auditory system, vibration of the basilar membrane in which the peak of the vibration travels from the base of the membrane to its apex.
What is the cochlea like?
A filter - organised in tonotopic map
What does the tonotopic map depend on?
- the neurons respond best to one frequency
- each frequency is associated with nerve fibers located at a specific place along the basilar membrane
What is a cochlear amplifier?
Amplifying effect done by outer hair cells
What is place theory?
The proposal that the frequency of a sound is indicated by the place along the organ of Corti at which nerve firing is highest. Modern place theory is based on Békésy’s traveling wave theory of hearing (movy basilar membrane)
Resolved vs unresolved harmonics?
Resolved= Harmonics in a complex tone that create separated peaks in basilar membrane vibration, and so can be distinguished from one another. Usually lower harmonics of a complex tone.
Unresolved= Harmonics of a complex tone that can’t be distinguished from one another because they are not indicated by separate peaks in the basilar membrane vibration. The higher harmonics of a tone are most likely to be unresolved.
What is noise? (like a truck going past)
A sound stimulus that contains many random frequencies.
What is temporal coding?
The connection between the frequency of a sound stimulus and the timing of the auditory nerve fiber firing.
Where in the brain does the info go?
sequence begins with the cochlear nucleus and continues to the superior olivary nucleus in the brain stem, the inferior colliculus in the midbrain, and the medial geniculate nucleus in the thalamus. Then to primary auditory cortex.
What are pitch neurons?
A neuron that responds to stimuli associated with a specific pitch
What is Presbycusis
A form of sensorineural hearing loss that occurs as a function of age and is usually associated with a decrease in the ability to hear high frequencies. Since this loss also appears to be related to exposure to environmental sounds, it is also called sociocusis.
What is Noise-induced hearing loss?
A form of sensorineural hearing loss that occurs when loud noises cause degeneration of the hair cells.
What is leisure noise?
Noise associated with leisure activities such as listening to music, hunting, and woodworking. Exposure to high levels of leisure noise for extended periods can cause hearing loss.
What is hidden hearing loss?
Hearing loss that occurs at high sound levels, even though the person’s thresholds, as indicated by the audiogram, are normal. Cause: background noise
