Blue Sky Science: How do we hear?

Jill Blair


How do we hear?

Sounds reach our ears from different locations and first travel through the ear into the ear canal. Then tiny bones inside the middle ear end up vibrating and pushing on a small window. This then gets a special membrane inside our ear to vibrate.

We then have a swirly-shaped sensory organ called the cochlea. Inside the cochlea, a vibrating membrane excites tens of thousands of cells called hair cells.

When the hairs atop the hair cells move, they open ion channels that bring chemicals into the cells and send information to the auditory nerve or cochlear nerve. That nerve sends information up to the brain.

If those hair cells don’t work, somebody experiences deafness or severe to profound hearing loss. That means they don’t understand speech or they can’t hear music.

To help them hear, we can do a surgery called cochlear implantation. In that surgery, a tiny electrode is placed inside the cochlea. We send pulses of electricity to that electrode which stimulates the auditory nerve. The auditory nerve can then again send information to the brain, like in normal hearing.

In my lab, we’re focusing on a few interesting questions. One of them has to do with whether people should receive one cochlear implant in one ear or a cochlear implant in both ears.
We are learning that when you give someone one cochlear implant, they are able to understand speech and language, but have a very difficult time understanding where sounds are coming from. Hearing speech and noise is difficult, and they have to work really hard.

With two cochlear implants, we see important benefits and it makes it much easier for someone to hear.