Noam Hassenfeld

It's called hidden hearing loss.

And it was only discovered a few years ago when researchers at Mass Eye and Ear realized just how easy it was to damage those louder nerve fibers.

The idea is that if you have tinnitus, at some point in the past, you probably damaged your hearing.

Specifically, you damaged those louder fibers.

But your symptoms might have gone away.

And because normal hearing tests don't focus on loud fibers, that damage stayed hidden.

And if your loud fibers get damaged, you're not going to have any issues having a conversation in a quiet room.

You're not going to have any issues on your hearing test.

But if you go somewhere like a bar or a restaurant, you might find that you suddenly can't make out what your friend is saying.

So Stefan took his patients with normal hearing test scores, and instead of giving them that classic hearing test again, he gave them a different one focused on loud fibers.

Like he suspected, a lot of them really struggled with the louder, echoey conversations because they had hidden hearing loss.

They had damage to their loud fibers.

And Stefan had a feeling that hidden hearing loss could be the thing causing his patients that had normal hearing test scores to have tinnitus.

So we ran a different test.

He placed tiny electrodes inside their ear canals and he played them a sound.

A click.

He recorded the electrical responses from that sound.

And that's going to show you different types of waveforms.

It's basically a squiggly line that shows neurons firing as a sound signal gets processed by the brain.

And when he looked at the early peaks, which show the auditory nerve in the inner ear, he saw way less firing than normal.