Theories of Hearing/ Theories of Pitch Perception
Place Theory of Hearing
• The most frequent question that comes to mind is that how can our brain sort out the sound waves
of different frequencies and intensities without any hindrance or problem?
• The answer lies in the studies donein this regard. They show that the basal membrane (inner most
region of the ear near the cochlea) and its associated areas are most sensitive to high pitched
frequency sounds, and the area near the cochlea is more sensitive to low- frequency sounds.
• The findings of these studies led to the formation of place theory of hearing, which says that
different areas in the basal membrane respond to different frequencies of sound; pitch corresponds
to the location of greatest stimulation along the basilar membrane.
• The most important shortcoming of this theory is that it is unable to explain the process of hearing,
i.e. sounds of low frequencies also trigger the neurons in the basal membrane and its associated
areas.
• Due to this incomplete explanation of auditory phenomena, an additional explanation came in the
form of “ frequency theory of hearing”.
Frequency Theory of Hearing
• This theory explains that the entire basal membrane acts as a microphone, vibrating in response to
sound i.e. activation occurs in the whole area in response to the vibration.
• The theory tends to explain that the nerve impulses in that region are directly connected/
associated with the frequencies ofsound to which they are exposed___ so the higher the pitch of
the sound, the more the nerves trigger and send messages to the brain.
• Both theories are important and useful in the sense that they provide the accurate description of
the whole auditory phenomena.Specifically, place theory gives a better explanation of processing
the high- frequency sounds and frequency theory tells us that how the low-frequency sounds are
encountered and dealt with.
Auditory Information Processing
• After leaving the ear, the auditory message is directly transmitted to the auditory cortex of the brain
with the complex series of neural interconnections
• Within the cortex, there are neurons that respond to selective sounds having specific features___
there are neurons also that respond only to specific pattern/ sort of sounds and not to the
intermittent sounds.
• Auditory cortex provides us with the “ map” of sound frequencies that furnishes our response to
the environmental stimuli.Auditory/ Hearing Damage
• Auditory damage occurs largely due to the following three major reasons besides some others:
1. Prolonged exposure to loud noise
2. Severe/ hard blow to the ear sensitive regions
3. Old age
(Others include illness, or damage to the middle or inner ear)
1. Prolonged Exposure to the Loud Noise
• It is also called stimulation deafness
• It includes various types of loud tones/ sounds such as speech, music, machinery,
• and other complex sounds
• The damage is irreversible as the receptors which are damaged do not regenerate
• Large amount of damage occurs between the frequency of 1000 Hz to 2000 Hz
2. Severe/ Hard Blow to the Ear Sensitive Regions
• Tinnitus refers to a "ringing in the ears" ____ it is usually a high-pitched tone.
• The origins of it may lie in either extreme stimulation (above 130 db) or in vascular
• blockage, or in muscle spasms i.e., in the tympanic muscles.
3. Old Age
• As people progress towards their old age, their hearing capability weakens in higher frequency ranges. This is primarily due to an over all degeneration .
• Environmental factors also play role in causing auditory damage along with old age.
Types of Hearing Impairment
1. Conduction Deafness: problem in conduction of air vibrations to the cochlea; the bones in the
middle ear do not function properly.
Treatment: microsurgery for replacing the affected bone with an artificial one.
2. Nerve Deafness: deafness caused by a damage to the neural mechanism that creates nerve impulses
or relays them to the auditory cortex; deafness may also be caused by a damageto the auditory cortex
itself.
Balance and the Role of Ear
• Several ear structures are related with the sense of balance of the person much more than playing their
roles in hearing phenomena
• Three tubes or the semi circular canals (inner ear) contain the fluid that moves when the head moves;
the rotational or angular movements are signaled to the brain.
The semicircular canals contain otoliths that are tiny motion- sensitive crystals. The otoliths can sense the
pull on our body exerted by gravity, as well as that by the acceleration of forward, backward, or up-anddown motion. When the person moves these crystals alsomove. Thus the system is familiar with the feeling
in case of different moves, and constantly strives for a perfectly balanced position; the otoliths can sense
immediately.
• The most frequent question that comes to mind is that how can our brain sort out the sound waves
of different frequencies and intensities without any hindrance or problem?
• The answer lies in the studies donein this regard. They show that the basal membrane (inner most
region of the ear near the cochlea) and its associated areas are most sensitive to high pitched
frequency sounds, and the area near the cochlea is more sensitive to low- frequency sounds.
• The findings of these studies led to the formation of place theory of hearing, which says that
different areas in the basal membrane respond to different frequencies of sound; pitch corresponds
to the location of greatest stimulation along the basilar membrane.
• The most important shortcoming of this theory is that it is unable to explain the process of hearing,
i.e. sounds of low frequencies also trigger the neurons in the basal membrane and its associated
areas.
• Due to this incomplete explanation of auditory phenomena, an additional explanation came in the
form of “ frequency theory of hearing”.
Frequency Theory of Hearing
• This theory explains that the entire basal membrane acts as a microphone, vibrating in response to
sound i.e. activation occurs in the whole area in response to the vibration.
• The theory tends to explain that the nerve impulses in that region are directly connected/
associated with the frequencies ofsound to which they are exposed___ so the higher the pitch of
the sound, the more the nerves trigger and send messages to the brain.
• Both theories are important and useful in the sense that they provide the accurate description of
the whole auditory phenomena.Specifically, place theory gives a better explanation of processing
the high- frequency sounds and frequency theory tells us that how the low-frequency sounds are
encountered and dealt with.
Auditory Information Processing
• After leaving the ear, the auditory message is directly transmitted to the auditory cortex of the brain
with the complex series of neural interconnections
• Within the cortex, there are neurons that respond to selective sounds having specific features___
there are neurons also that respond only to specific pattern/ sort of sounds and not to the
intermittent sounds.
• Auditory cortex provides us with the “ map” of sound frequencies that furnishes our response to
the environmental stimuli.Auditory/ Hearing Damage
• Auditory damage occurs largely due to the following three major reasons besides some others:
1. Prolonged exposure to loud noise
2. Severe/ hard blow to the ear sensitive regions
3. Old age
(Others include illness, or damage to the middle or inner ear)
1. Prolonged Exposure to the Loud Noise
• It is also called stimulation deafness
• It includes various types of loud tones/ sounds such as speech, music, machinery,
• and other complex sounds
• The damage is irreversible as the receptors which are damaged do not regenerate
• Large amount of damage occurs between the frequency of 1000 Hz to 2000 Hz
2. Severe/ Hard Blow to the Ear Sensitive Regions
• Tinnitus refers to a "ringing in the ears" ____ it is usually a high-pitched tone.
• The origins of it may lie in either extreme stimulation (above 130 db) or in vascular
• blockage, or in muscle spasms i.e., in the tympanic muscles.
3. Old Age
• As people progress towards their old age, their hearing capability weakens in higher frequency ranges. This is primarily due to an over all degeneration .
• Environmental factors also play role in causing auditory damage along with old age.
Types of Hearing Impairment
1. Conduction Deafness: problem in conduction of air vibrations to the cochlea; the bones in the
middle ear do not function properly.
Treatment: microsurgery for replacing the affected bone with an artificial one.
2. Nerve Deafness: deafness caused by a damage to the neural mechanism that creates nerve impulses
or relays them to the auditory cortex; deafness may also be caused by a damageto the auditory cortex
itself.
Balance and the Role of Ear
• Several ear structures are related with the sense of balance of the person much more than playing their
roles in hearing phenomena
• Three tubes or the semi circular canals (inner ear) contain the fluid that moves when the head moves;
the rotational or angular movements are signaled to the brain.
The semicircular canals contain otoliths that are tiny motion- sensitive crystals. The otoliths can sense the
pull on our body exerted by gravity, as well as that by the acceleration of forward, backward, or up-anddown motion. When the person moves these crystals alsomove. Thus the system is familiar with the feeling
in case of different moves, and constantly strives for a perfectly balanced position; the otoliths can sense
immediately.
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