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Hearing Our auditory sense

We hear sound WAVES The height of the wave gives us the amplitude of the sound. The frequency of the wave gives us the pitch if the sound.

Transduction in the ear Sound waves hit the eardrum then anvil then hammer then stirrup then oval window. Everything is just vibrating. Then the cochlea vibrates. The cochlea is lined with mucus called basilar membrane. In basilar membrane there are hair cells. When hair cells vibrate they turn vibrations into neural impulses. Sent then to thalamus up auditory nerve. It is all about the vibrations!!!

Pitch Theories Place Theory and Frequency Theory

Place Theory Different hairs vibrate in the cochlea on the basilar membrane when they different pitches. So some hairs vibrate when they hear high and other vibrate when they hear low pitches. But this doesn’t explain low-pitch since we haven’t found specific positions for those on the BM

Frequency Theory All the hairs vibrate but at different speeds. – If the frequency of the sound is 100 waves per second then the neuron fires at 100 pulses per second. – But we can hear frequencies above 1000 waves per second but can’t fire neurons faster than 1000 pulses per second.

Deafness Conduction Deafness Something goes wrong with the sound and the vibration on the way to the cochlea. You can replace the bones or get a hearing aid to help. Nerve (sensorineural) Deafness The hair cells in the cochlea get damaged. Loud noises can cause this type of deafness. NO WAY to replace the hairs. Cochlea implant is possible.

Cochlear Implants Cochlear implants are electronic devices that enable the brain to hear sounds.