How do whales catch sounds? How did Beethoven listen to music? Whales use the lower jawbone to catch vibrations that travel through water and transmit them to their ears. Beethoven held a baton between his teeth and pressed it tightly against his piano. He listened by transmitting the piano sound vibrations from his teeth to his hearing organs by way of his skull.

As these examples show, there are two transmission routes for sounds and voices: the air and bones. Vibrations that reach our ears through the air are known as air-transmitted sound. People normally refer to these vibrations when discussing hearing. Vibrations that reach our ears through bones are called bone-transmitted sound. Thus, sounds and voices reach our ears as vibrations through the air or through our bones and skin.

Let us begin our explanation with air-transmitted sound. We normally "hear sounds with our own ears" when detecting vibrations in the air. Human speech, radio, and television sounds vibrate the surrounding air. The outer ear collects and guides these vibrations into our external auditory canal. Vibrations reach and shake the eardrum through the external auditory canal. Our middle ear amplifies this vibratory motion, which we perceive as sounds the moment it swings the tip of our auditory nerve floating in lymph that fills the cochlear canal in the inner ear.

Bone-transmitted sound refers to "directly transmitted vibrations." These vibrations do not bypass either the outer ear or middle ear, and travel straight to the cochlear canal in the inner ear. Upon arriving in the cochlear canal, this vibratory motion shakes the auditory nerve floating in lymph. We can still hear our own voice when speaking with our ears covered. We can do this because our bones and skin transmit the vibrations of our speech. Our own voice sounds like someone else's when we utter words with ears covered. We sense this impression because closed ears shut out air-transmitted sound. We receive most vibrations from our bones and skin when covering our ears. Our own voice sounds strange when speaking with our ears covered because the voice we always hear and recognize as our own is a mixture of air-transmitted and bone-transmitted sound.

We can hear our own voice when covering our mouth or ears with our hands, then saying something. We can catch our voice in such experiments thanks to bone conduction. However, our own voice sounds different from our normal one when speaking with covered mouth or ears. We experience this change because we only catch bone-transmitted sound under such circumstances. The opposite also holds true. Our own voice sounds strange when taping it and playing it back because a tape recorder only catches air-transmitted sound.

Our bones transmit voices. We can hear through our bones by using a highly sensitive vibration sensor to collect the vibrations of the vocal cords (that vibrate the bones) and converting these vibrations into electric audio signals.

Bone conduction microphones form another technical basis. The microphone cords use a highly sensitive vibration sensor to collect vibrations that reach the skull from the vocal cords and convert this vibratory motion into audio signals. You can wear these devices all over your head to pick up vibrations, provided they are mounted on a relatively solid section of your head. We offer two types of bone conduction microphones: an "ear microphone" that picks up vibrations in the auditory canal, and a headset that captures vibrations on the head. We equipped both products with corrective circuits optimized for converting bone-transmitted sound into clear voices. These products are compatible with various types of telecommunications equipment.

We have developed communications tools that provide high added values in various fields by applying the bone conduction mechanism to a broad range of cutting-edge telecommunications technology. Our achievements include hands-free communications systems for various uses (listening-only and two-way models), a bone conduction hearing aid incorporating a bone conduction speaker , and a helmet-type communications system. Contact Us for your Needs :