frequency (pitch): dimension of frequency determined by wavelength of sound…measured in hertz (hz)...
TRANSCRIPT
Frequency (pitch): Dimension of
frequency determined by wavelength of
sound…measured in hertz (Hz)
Humans can hear sounds at
frequencies from about 20Hz to
20,000Hz. We hear sounds best at around 3,000 to
4,000Hz, where human speech is centered.
Intensity
(Loudness):
Amount of energy
in a wave
determined by
amplitude relates to
perceived loudness.
Loudness is
measured in
decibels.
70dB
120dB
Richard Kaylin/ Stone/ Getty
Images
Pinna collects sound
control
vestibular
sense…balance
to the cochleatympanic
membrane
Coiled, bony, fluid-filled tube in the inner ear that
transduces sound vibrations to auditory signals.
Frequency Theory states that the rate of nerve
impulses traveling up the auditory nerve matches
the frequency of a tone, thus enabling us to sense
its pitch.
Sound
Frequency
Auditory Nerve
Action Potentials
Theories of Audition
Place Theory suggests that sound frequencies
stimulate basilar membrane at specific places
resulting in perceived pitch.
http://www.pc.rhul.ac.uk
Because we have two ears sounds that reach one ear
faster than the other makes us localize the sound.
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The older we get, we tend to lose the ability
to detect the higher frequency (pitch) sounds
Why do we lose the ability to detect the upper frequencies
as we age?
Due to the everyday sounds we expose our ears to…●generally any sound loud enough to produce tinnitus
(ringing of the ears) causes some damage (85db)●over the years, small amounts of damage accumulate●referred to as Noise Induced Hearing Loss (NIHL)
High intensity (loud) sounds can actually tear off the hair
cells of the inner ear
Healthy…three rows of outer hair
cells and one row of inner hair
cells are seen.
Damaged…
especially “outer”
hair cells
Conduction Deafness: Hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea.●may be “corrected” with surgery or hearing
aides
Sensorineural Deafness: Hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve, also called nerve deafness.●this is a permanent condition
A cochlear implant is a small, complex electronicdevice that can help to provide a sense of sound to a person who is profoundly deaf or severely hard-of-hearing. The implant consists of an external portion that sits behind the ear and a second portion that is surgically placed under the skin. An implant has the following parts:
oA microphone, which picks up sound from the environment. oA speech processor, which selects and arranges sounds picked up by the
microphone. oA transmitter and receiver/stimulator, which receive signals from the speech
processor and convert them into electric impulses. oAn electrode array, which is a group of electrodes that collects the impulses
from the stimulator and sends them to different regions of the auditory nerve.
An implant does not restore normal hearing. Instead, it can give a deaf person a useful representation of sounds in the environment and help him or her to understand speech.
Information from…http://www.nidcd.nih.gov/health/hearing/coch.asp
Wolfgang Gstottner. (2004) American
Scientist, Vol. 92, Number 5. (p. 437)
Total cost of surgery = $40,000
