What happen the path of sound from the outer ear to interpretation by the brain detailing what happens at each step in the pathway?

Answer 1

the mechanisms of sound transduction are briefly summarized below:

1. Sound waves enter the external ear and are funneled toward the tympanic membrane by the shape of the outer ear.
2. Variation in air pressure due to sound waves causes the tympanic membrane to vibrate. The wave frequency will determine the vibration rate.
3. Tympanic vibrations cause the malleus to move. Because the three ossicles are connected, this vibration is transduced to the stapes via the incus.
4. Movement of the stapes vibrates the oval window. Significant amplification of sound waves occurs due to the small size of the window.
5. Pressure changes transduced through the oval window vibrate the perilymph in the scala vestibuli which are transmitted across the vestibular membrane to the endolymph of the cochlear duct, and also up the scala vestibuli and down the scala tympani much the way waves move through the ocean.
6. Perilymph vibrations move the basilar membrane. The frequency of the basilar vibrations determine the pitch interpreted by the auditory area of the brain.
7. Hair cells lying along the basilar membrane are moved as the membrane vibrates. The cilia of the hair cells are in contact with the tectorial membrane. As the hair cells move, stereocilia bend opening ion channels and developing a generator potential. If threshold is reached, a neurotransmitter is released, exciting an afferent neuron.
8. Action potentials are transmitted along the cochlear branch of the vestibulocochlear nerve, activating auditory pathways in the central nervous system, eventually terminating in the auditory area of the temporal lobe of the cerebral cortex.

Answer 2

Sound waves enter the outer ear and travel through the ear canal to reach the eardrum. The eardrum vibrates in response to the sound waves, transmitting vibrations to the three small bones in the middle ear. These bones amplify the vibrations and transmit them to the cochlea in the inner ear, where hair cells convert the vibrations into electrical signals. These signals are then sent through the auditory nerve to the brainstem and eventually to the auditory cortex in the brain for interpretation of the sound.