Cochlear microphonics are electrical potentials recorded in response to acoustic stimuli, reflecting the waveform of the sound and generated in cochlear hair cells. They are not of biological origin, as they exhibit unique properties such as lack of latent and refractory periods, resistance to ischemia, and persistence after death. Clinically, they are used to assess cochlear integrity since they vanish when hair cells are damaged.

1. COCHLEAR MICROPHONICS
Dr Parth

2. COCHLEAR MICROPHONICS
Dr Parth
An electrode placed in any cochlear
compartment, or even near the cochlea,
electrical potentials can be recorded in
response to acoustic stimuli. These
responses follow the wave form of the
stimulus, and are known as cochlear
microphonics

3. Cochlear microphonics develop in the hair
cells of the cochlea before the
development of action potentials in
auditory nerve fibers

4. The following observations indicate that cochlear
microphonics are not of biological origin.
auditory nerve fibers
They
do not
have a
latent
period
They do
not have
a
refractor
y period
They do
not
show
fatigue
and are
resistan
t to
ischemi
a and
hypoxia
Their
frequenc
y can be
unusuall
y high
for any
biologica
l signal
They
persist
several
hours
after
death!

5. They are called “microphonics” because when these
potentials are fed into a speaker through an
amplifier, the original sound is accurately
reproduced. This proves that the waveform of
cochlear microphonic potential is an exact replica of
the sound wave that produces it.

6. Cochlear
microphonics are
produced through
the piezoelectric
effect, a property
exhibited mostly
by certain crystals
that generate
electricity when
subjected to
mechanical
stresses
Cochlear
microphonics do
not have a
significant
physiological role
in the hearing
mechanism. At
best, they might
have a role in
boosting receptor
excitation
Cochlear
microphonics have
been put to clinical
use for testing the
integrity of the
cochlea since they
disappear when
the hair cells are
damaged
the sound wave that produces it.

7. COCHLEAR MICROPHONICS
Dr Parth

8. COCHLEAR MICROPHONICS
Dr Parth
An electrode placed in any cochlear
compartment, or even near the cochlea,
electrical potentials can be recorded in
response to acoustic stimuli. These
responses follow the wave form of the
stimulus, and are known as cochlear
microphonics

9. Cochlear microphonics develop in the hair
cells of the cochlea before the
development of action potentials in
auditory nerve fibers

10. The following observations indicate that cochlear
microphonics are not of biological origin.
auditory nerve fibers
They
do not
have a
latent
period
They do
not have
a
refractor
y period
They do
not
show
fatigue
and are
resistan
t to
ischemi
a and
hypoxia
Their
frequenc
y can be
unusuall
y high
for any
biologica
l signal
They
persist
several
hours
after
death!

11. They are called “microphonics” because when these
potentials are fed into a speaker through an
amplifier, the original sound is accurately
reproduced. This proves that the waveform of
cochlear microphonic potential is an exact replica of
the sound wave that produces it.

12. Cochlear
microphonics are
produced through
the piezoelectric
effect, a property
exhibited mostly
by certain crystals
that generate
electricity when
subjected to
mechanical
stresses
Cochlear
microphonics do
not have a
significant
physiological role
in the hearing
mechanism. At
best, they might
have a role in
boosting receptor
excitation
Cochlear
microphonics have
been put to clinical
use for testing the
integrity of the
cochlea since they
disappear when
the hair cells are
damaged
the sound wave that produces it.

13. COCHLEAR MICROPHONICS
Dr Parth

14. COCHLEAR MICROPHONICS
Dr Parth