A hearing aid . . . in your mouth? Sounds strange, right? But researchers in Shanghai, China, published a study about that possibility. False teeth may one day double as hearing aids.
When sound waves contact material, vibrations form. Hearing occurs when sound travels through air (called “air conduction”) into the ear canals and is interpreted by the brain. But sound can also travel through liquids and solids, including bone. The waves actually travel faster through solids because the molecules of a solid are more tightly packed together. Those closer-packed molecules transmit vibrations faster. For some folks with outer or middle ear problems, bone conduction can help gather sound and bring it into the brain.
In bone conduction, sound waves bypass the eardrum. The vibrations go directly to the inner ear. That’s the technique Thomas Edison used when he bit pianos. (See Tunes with Teeth.) Famous composer Ludwig van Beethoven used the same technique as he became deaf. He held one end of a wooden stick between his teeth and rested the other end on his piano.
Have you ever seen someone wearing bone conduction headphones, also known as “bonephones”? Most models wrap around the back of the head with vibration-generating pads that sit just above the ears or cheeks. The vibrations travel through the wearer’s skin and bone to the inner ear. Since bone conduction headphones don’t use the ears, a hearing wearer can listen to music while still being able to hear the sounds of the outside world. That makes bonephones useful to runners or cyclists who need to stay alert while exercising outside.
Researcher Jianxiang Tao and his colleagues knew that bone conduction through teeth could work well. But what about artificial teeth? In the study, 38 people listened for sounds through tooth implants, natural teeth, or their mastoid bones (located just behind the ear). According to the researchers, bone conduction through the implants worked as well as or better than through the natural teeth or mastoid bone.
Hearing aids that use bone conduction, even through the teeth, already exist. The SoundBite hearing system uses a vibrating piece clipped to the teeth along with a behind-the-ear piece that transmits sound to the mouthpiece. But the idea of conducting sound with a false tooth is new.
The electronics that impart sound vibrations could be built into the part of a false tooth anchored in the jawbone, Tao told ScienceNews. And the researchers write that dental implant hearing aids could offer “excellent concealment, good comfort, and improved quality of sound.”
Why? The study of God’s creation shows us the principles He built into the world. When we learn how something like bone conduction works, we can use that knowledge to serve others.