Audition Flashcards
Through which mechanism do we perceive low-frequency
sounds (up to about 100 Hz)?
At low frequencies, the basilar membrane vibrates in synchrony with the sound waves, and each responding axon in the auditory nerve sends one action potential per sound wave.
How do we perceive middle-frequency sounds (100 to
4000 Hz)?
At intermediate frequencies, no single axon fires an action potential for each soundwave, but different axons fire for different waves, andso a volley (group) of axons fires for each wave.
How do we perceive high-frequency sounds (above
4000 Hz)?
At high frequencies, the sound causes maximum vibration for the hair cells at one location along the basilar
membrane.
What evidence suggests that absolute pitch depends on
special experiences?
Absolute pitch occurs almost entirely among people who had early musical training and is also more common among people who speak tonal languages, which require greater attention to pitch
How is the auditory cortex like the visual cortex?
Any of the following:
(a) Both vision and hearing
have “what” and “where” pathways.
(b) Areas in the
superior temporal cortex analyze the movement of both
visual and auditory stimuli. Damage there can cause
motion blindness or motion deafness.
(c) The visual
cortex is essential for visual imagery, and the primary
auditory cortex is essential for auditory imagery.
(d)
Both the visual and auditory cortices need normal
experience early in life to develop normal sensitivities
What is one way in which the auditory and visual cortices
differ?
Damage to the primary visual cortex leaves
someone blind, but damage to the primary auditory
cortex merely impairs the perception of complex sounds
without making the person deaf
What kinds of sounds most strongly activate the auditory
cortex?
Each cell in the primary auditory cortex has a preferred frequency.Many or most cells respond best to complex sounds
that include harmonics. Outside the primary auditory
cortex, most cells respond to “auditory objects” that
mean something
Which type of hearing loss would be more common
among members of rock bands and why?
Nerve deafness is common among rock band members because their frequent exposure to loud noises causes damage to the cells of the ear
Which method of sound localization is more effective for
an animal with a small head? Which is more effective for
an animal with a large head? Why?
An animal with a small head localizes sounds
mainly by differences in loudness because the ears
are not far enough apart for differences in onset time
to be very large. An animal with a large head localizes
sounds mainly by differences in onset time because
its ears are far apart and well suited to noting differences in phase or onset time
Which method of sound localization is more effective for
an animal with a small head? Which is more effective for
an animal with a large head? Why?
An animal with a small head localizes sounds
mainly by differences in loudness because the ears
are not far enough apart for differences in onset time
to be very large. An animal with a large head localizes
sounds mainly by differences in onset time because
its ears are far apart and well suited to noting differences in phase or onset time
Which method of sound localization is more effective for
an animal with a small head? Which is more effective for
an animal with a large head? Why?
An animal with a small head localizes sounds
mainly by differences in loudness because the ears
are not far enough apart for differences in onset time
to be very large. An animal with a large head localizes
sounds mainly by differences in onset time because
its ears are far apart and well suited to noting differences in phase or onset time
Which method of sound localization is more effective for
an animal with a small head? Which is more effective for
an animal with a large head? Why?
An animal with a small head localizes sounds
mainly by differences in loudness because the ears
are not far enough apart for differences in onset time
to be very large. An animal with a large head localizes
sounds mainly by differences in onset time because
its ears are far apart and well suited to noting differences in phase or onset time
Sound wave
are periodic compressions of air, water, or other media
they vary in their frequencies and amplitude
What are the properties of sound
Amplitude
Frequency
Timbre
Amplitude
refers to the intensity of the sound wave
Frequency
is the number of compressions per second and is measured in hertz (Hz) Related to the pitch (high to low)
Timbre
is tone quality or tone complexity
What factors determine the ability to recognize high
frequencies?
Age
Children hear higher frequencies than adults; the ability to recognize high frequencies diminishes with age and
exposure to loud noises
Structures of the Ear
Outer ear
inner ear
middle ear
Outer Ear
Responsible for:
– Altering the reflection of sound waves into the
middle ear from the outer ear
– Helping us to locate the source of a sound
Theories of Pitch Perception
Place theory
Frequency theory
Place theory
each area along the basilar
membrane has hair cells sensitive to only
one specific frequency of sound wave
Frequency theory
the basilar membrane
vibrates in synchrony with the sound and
causes auditory nerve axons to produce
action potentials at the same frequency
Inner Ear
Connects to three tiny bones (malleus, incus, & stapes) that transform waves into stronger waves to the oval window
The oval window is a membrane in the inner
ear: transmits waves through the viscous
the fluid of the inner ear
The inner ear contains a snail-shaped structure called the cochlea contains three fluid-filled tunnels (scala vestibuli, scala media, & the scala tympani)
Inner Ear
Connects to three tiny bones (malleus, incus, & stapes) that transform waves into stronger waves to the oval window
The oval window is a membrane in the inner
ear: transmits waves through the viscous
the fluid of the inner ear
The inner ear contains a snail-shaped structure called the cochlea contains three fluid-filled tunnels (scala vestibuli, scala media, & the scala tympani)
Inner Ear
Connects to three tiny bones (malleus, incus, & stapes) that transform waves into stronger waves to the oval window
The oval window is a membrane in the inner
ear: transmits waves through the viscous
the fluid of the inner ear
The inner ear contains a snail-shaped structure called the cochlea contains three fluid-filled tunnels (scala vestibuli, scala media, & the scala tympani)
Hair cells in the Ear
Hair cells are auditory receptors that lie between the basilar membrane and the tectorial membrane in the cochlea
current pitch theory
current pitch theory combines modified versions of both the place
theory and frequency theory:
– Low-frequency sounds best explained by
the frequency theory
– High-frequency sounds best explained by
place theory
Variations in Sensitivity to Pitch: Amusia
the impaired detection of frequency changes (tone deafness)
Associated with a thicker than average auditory cortex in the right hemisphere, but fewer connections from the auditory cortex to the frontal cortex
Variations in Sensitivity to Pitch: Amusia
the impaired detection of frequency changes (tone deafness)
Variations in Sensitivity to Pitch: Absolute pitch perfect pitch
is the ability to hear a note and identify it
1. Genetic predisposition may contribute to it
2. The main determinant is early and extensive
musical training
Auditory Cortex
The primary auditory cortex (area A1) is the destination for most information from the auditory system
Location: in the superior temporal cortex
Each hemisphere receives most of its information from the opposite ear
Organization of the Auditory Cortex
- Superior temporal cortex allows detection of
the motion of sound - Area A1 is important for auditory imagery
Functions of the Auditory Cortex
- Necessary for processing information but not hearing
- Provides a tonotopic map in which cells in the primary auditory cortex is more responsive to preferred tones
3.
what happens if the Primary auditory cortex is damaged
Damage to A1 does not necessarily cause deafness unless damage extends to the subcortical areas
Auditory Areas
- Areas around the primary auditory cortex
Hearing Loss types
Conductive or middle ear deafness
Nerve deafness or inner ear deafness
Conductive/Middle Ear Deafness
Occurs if bones of the middle ear fail to transmit sound waves properly to the cochlea
Conductive/Middle Ear Deafness causes
Can be caused by disease, infections, or
tumorous bone growth
Normal cochlea function
Normal cochlea and auditory nerve allow
people to hear their own voice clearly
How to treat Conductive/Middle Ear Deafness
Can be corrected by surgery or hearing aids that amplify the stimulus
Nerve or Inner-Ear Deafness
Results from damage to the cochlea, the hair cells, or the auditory nerve
Can vary in degree Can be confined to one part of the cochlea People can hear only certain frequencies
Nerve or Inner-Ear Deafness Causes
Can be inherited or caused by prenatal problems or early childhood disorders
Auditory impairment: Tinnitus
Frequent or constant ringing in the ears is experienced by many people with nerve deafness.
Sometimes occurs after damage to the cochlea
How do age, and attention affect hearing
Brain areas responsible for language comprehension become less active
older people have a decrease in the inhibitory neurotransmitters in the auditory portions of the brain
what improves listining during speaking?
Attention improves if the listener watches
the speaker’s face
factors that affect sound localization
Depends upon comparing the responses of the two ears
Three cues:
– Sound shadow
– Time of arrival
– Phase difference
how humans localize sounds
Humans localize low frequency sound by phase difference and high frequency sound by loudness differences
Mechanisms of Sound Localization
they are three
High-frequency sounds (2000 to 3000Hz)
create a “sound shadow”
- Difference in time of arrival at the two ears
most useful for localizing sounds with
sudden onset - Phase difference between the ears
provides cues to sound localization with
frequencies up to 1500 Hz
Mechanical Senses
The mechanical senses respond to pressure, bending, or other distortions of a receptor
Audition is a complex mechanical sense
Vestibular Sensation
The vestibular sense: system that detects the position and movement of the head
The vestibular organ is in the ear and is
adjacent to the cochlea
what is Vestibular Organ
Comprises two otolith organs (the saccule and utricle) and three semicircular canals
Semicircular canals
are filled with a jellylike substance and hair cells that are
activated when the head moves
People with damage to the vestibular system have trouble
reading street signs while walking. Why?
The vestibular system enables the brain to shift
eye movements to compensate for changes in head
position. Without feedback about head position, a person would not be able to correct the eye movements,
and the experience would be like watching a jiggling
book page.
