From Sound to Hearing

Sound vibrations move through the air like waves moving across water. Hearing begins when the vibrations reach the outer ear (1), which acts to funnel the vibrations through the ear canal (2) toward the eardrum (3).

The inset shows sound vibrations interacting with the eardrum, before transferring to a series of three tiny bones in the middle ear (4). These bones further amplify the vibrations of the eardrum, then transfer them to a sensory organ in the inner ear, the cochlea (5).

The Cochlea

The cochlea is filled with fluid, and lined with tens of thousands of tiny hair cells. The following figures (A-E) show increasingly enlarged electron microscope images of the cochlea and hair cells. Figure A shows a more global view of a sound wave’s journey to the cochlea.

The next figure illustrates the relationship between hair cells and sound frequency detection.  The hair cells lining the cochlea have varying sensitivity for detecting sounds of different frequencies. Hair cells located at the base of the Cochlea detect higher frequency sounds. Middle frequencies are detected by hair cells at the center of the winding Cochlea, and hair cells at the apex of the Cochlea detect lower tones.

As sound vibrations pass through the fluid of the cochlea, they cause the hair cells to move. This motion causes electrical signals to be sent along the auditory nerve, which are then processed by the brain into the sounds we hear.

See the Video: How Hearing Works for a brief summary of the process of hearing.


Video text

The next three videos will take you on a journey from sound to hearing…then investigate what can go wrong along the way.

From sound to HearingThe Sum of the Parts

This video will take you on a journey from sound to hearing. Along the way you will see the role of hair cells lining the Cochlea in processing the full range of sound frequencies.


Sensorineural Hearing LossSensorineural Hearing Loss

Sensorineural hearing loss originates in the inner ear, where the hair cells of the Cochlea become damaged or missing. Without these hair cells the brain cannot interpret sounds..


Conductive Hearing LossConductive Hearing Loss

Conductive hearing loss is a problem in the outer or middle ear that prevents sound from reaching the inner ear. Middle ear implants or hearing aids can help.


Click here to go back to “The Nature of Sound”…and here if you want to go to “When Hearing Fails”.

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Audiology Screening

At one of PNWA’s events, which was very informative, I learned that tinnitus may be a sign of hearing loss. I went for a screening and found that my hearing is normal. My mom, who wears aids, also had a screening and was happy to know that her hearing level had not changed. The staff is very friendly and professional, and made sure we understood our screening results. We will continue to see PNwA for our hearing health. We highly recommend them.

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I was so impressed with the professionalism and friendliness of the people I interacted with. I learned so many facts about how my ears function. Getting to see my ear drum was really cool. The way the graphs were displayed on a large screen made it so easy to understand the status of my hearing ability. I would encourage you to have your hearing checked sooner rather then later.

Hearing Aids

I am very happy with NW Pacific Audiologist. I would recommend you to go there. These people are so wonderful and smile. I feel they are taking time to listen what’s your hearing problem. They will work with you. Thank you very much.

Finally .. a solution I can work with

I am new to the hearing loss world. I wasnt aware I needed hearing aids until I had my evaluation at Pacific Northwest. the care I have recieved and the honest concern for me to reach my full hearing potential was a fresh breath of air. I have been more then satisfied with my care and my aids are beyond what I could have imagined.

New Patient

The office staff is friendly and professional. Initial testing was complete and data gathered was shared in a timely fashion in layman’s terms. I am happy with my Resound hearing devices; they are comfortable and easy to use. Dr. Ian Odgear explained the components of my devices and how to synch with my iPhone and other electronics. Nice guy!

…and more than 400 other 5-Star Reviews!

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