Dr's Casebook: Why your ears ring when you hear a deafening sound

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I was in Egypt exactly three years ago, visiting the Step Pyramid in Saqqara.

Dr Keith Souter writes: Repair work was being carried out using traditional methods including ropes and pulleys.

Suddenly, ropes somehow broke and a heavy load crashed to the ground from high up on the pyramid and landed with a terrific noise close to myself and my guide.

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I went deaf for a few moments and then I heard a ringing noise.

Photo: AdobePhoto: Adobe
Photo: Adobe

It cleared after a few minutes.

This was typical of a deafening sound.

When this happens it is the interaction between the smallest muscle in the body and the smallest bone, which actually protect the hearing.

The muscle is called stapedius and the bone is the stapes.

You have one of each in both ears.

The stapedius muscle is only about a millimetre long.

Its purpose is to limit the vibrations in the ear when you hear these very loud sounds.

It does so by stabilising the stapes bone in the middle ear.

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You actually have three small bones in the middle ear chamber called the ossicles.

Their individual names are the malleus, incus and stapes, or in English the hammer, anvil and stirrup.

The stirrup is the one that is in contact with the ear drum.

When the stapedius muscle contracts it stabilises the stapes and limits the very loud noise by tightening the three ossicle bones.

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This prevents damage to the bones and the ear from these very loud noises.

It was a 16th century Sicilian anatomist called Giovanni Filippo Ingrassia who first described both the stapedius muscle the tiny stapes bone.

The stapedius muscle is supplied by a special branch of the seventh cranial nerve, known as the Facial Nerve.

This is in fact why Bell’s palsy, a temporary paralysis of one side of the face, which is supplied by the Facial Nerve, is often followed by hyperacusis.

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This is a condition that affects how sounds are perceived and because the stapedius doesn’t work properly there is no damping effect from it on the stapes.

Loud noises and even everyday noises like telephones can hurt.

If you are subject to this, then there are treatments that your doctor can advise about, like sound therapy and CBT which might help.

Hearing aids can also be tweaked.

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