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Hearing Motors in the Ears ? Fire Up Your Engine

A new study out of the University of Utah, co-authored by the Chair of the Bioengineering Department, Dr. Richard Rabbitt, has demonstrated that the human ear actually has tiny, “flexoelectric motors” that rev up to better enable us to hear by amping up sounds mechanically rather than neurologically.

In other words, your ears have tiny motors to soup up your hearing – all the more reason to take care of your hearing today and tomorrow.

In an interview published by the University of Utah News Center, Professor Rabbit explained, “We are reporting discovery of a new nanoscale [really teeny] motor in the ear. The ear has a mechanical amplifier in it that uses electrical power to do mechanical amplification.” This function of the ear is more like a Fender amp than anatomical bits that have long been thought to be the main source of sound.

The Cochlea

The cochlea is a fluid-filled organ deep within the ear. Its snail-shaped shell is lined with millions of tiny, hair-like fibers that convert sound vibrations into electrical impulses that are sent to the brain for processing.

The Utah News indicated that, “Previous research elsewhere indicated that hair cells within the cochlea of the inner ear can “dance” – elongate and contract – to help amplify sounds.

The new study shows sounds also may actually be amplified by “dancing” of stereocilia, which are the 50 to 300 hair-like nanotubes projecting from the top of each [cochlear] hair cell.”

William Brownell, a co-author of the study and professor of Otolaryngology at Baylor Collage of Medicine in Houston, whimsically described the discovery in terms we can all understand.

Brownell says the new study shows how the flexoelectric effect can account for the amplification of sound in the cochlea. Stereocilia essentially are membranes that have been rolled into tubes so the fact that a membrane can generate acoustic [mechanical] energy is novel. Imagine hearing a soap bubble talk.”

Another useful analogy comes from Professor Rabbit. “It’s like a car’s power steering system,” Rabbitt explained. You turn the wheel and mechanical power is added. Here [in the cochlea] the incoming sound is like your hand turning the wheel, but to drive, you need to add power to it. These [newly-studied] hair bundles add power to the sound.”

Flexoelectrical Energy

Katie Brenemen, a bioengineering doctoral student at the University of Utah and co-author of the study, stated that this energy may also be a part of digestion and memory formation. In other words, flexoelectrical energy may be a newly introduced source of power used throughout the body, not just at the end of the cochlear hair-like projections.

What makes the study so interesting is the way the body generates mechanical energy. Muscles and tendons flex and relax based on instructions from the brain so mechanical energy, of and by itself, is produced and used everyday for everything from walking to putting away the groceries.

However, this unusual, ground-breaking study shows that mechanical energy can also be made with delicate, tiny body parts that can only be seen under a microscope. The stereocilia at the end of each hair projection floating in cochlear fluid is invisible to the human eye

. In a recent post by Ed Yeates of KKSL newsradio Professor Rabbitt was quoted as saying, “What we are reporting here is a new motor that really hasn’t been understood in the past. It’s the stereocilia, the little tubes on the top of the cell.” Inside the inner ear, the little dancing hair-like tubes actually act like electric motors.” [that amplify sound before being sent to the brain where it will be further processed.]

Help for Hearing Loss?

Any discovery in how we hear and process sound offers hope to those with hearing loss. And the research won’t stop with the cochlea. Apparently flexoelectrical energy is produced throughout the body so studies will soon be underway examining this newly discovered physiological function.

Vroom. Vroom. Your ears have motors to help you hear better, more clearly and keenly. But additional research has also indicated that damage to the hair like projections that wave back and forth in the cochlear fluid is irreversible.

So even though you got millions of tiny amps boosting sound before transmission to the brain, these mechanisms are still delicate. It’s important, whether you are ten years of age or 100, to protect what you’ve got.

And despite this intriguing report from the University of Utah and Baylor College of Medicine, your ears are still delicate. And hearing is one of the things that improves life’s quality.

So begin now by protecting you hearing when you are exposed toe excessive noise. Earplugs will keep these tiny motors roaring for years to come.

If you suspect your ear motors may not be running as strong as they used, see a hearing professional for a hearing evaluation and have you stereocilia checked out and tuned up. There’s a lot to hear so do what you can to keep your motors running.

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