vibrations or what we conceive as sounds reach our ears (1) through the air or (2) through our bones and skin. The auditory nerve in our inner ear detects both types of vibratory motion as sound immediately upon arrival. We would like to explain how these vibrations or sounds travel to the auditory nerve as follows: 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.

As explained above, vibrations or what we conceive as sounds reach our ears (1) through the air or (2) through our bones and skin. The auditory nerve in our inner ear detects both types of vibratory motion as sound immediately upon arrival. We would like to explain how these vibrations or sounds travel to the auditory nerve as follows: 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. Hearing through the bones and skin offers many advantages because it does not require you to lend your ear to air-transmitted sound. The greatest advantage is complete freedom in both ears. You can catch sounds in your surroundings and have natural conversations without disconnecting your bone conduction speakers. You can use earplugs in combination to protect your hearing against loud noise. Bone conduction speakers serve various occasions and demands. You can use them in water and other special environments.

Though we produce our voice by vibrating the vocal cords, other people catch our vibrations released in the air with their ears. That's how others perceive our voice. The vibratory motion of the vocal cords travels to our own hearing organs through two transmission routes: the air and our skull. 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. photo Voice transmitted through the bones is the same as converting vocal cord vibrations into audio signals upon reception by the skull. You can catch cranial vibrations or voices in airless environments. Hearing aids incorporating the bone conduction mechanism offer users many advantages. These devices are easy to waterproof (for outdoor and underwater use), offer excellent tolerance to noise (thus less susceptible to external noise) and flexible to wear (by allowing you to position the microphone away from your mouth). You can use hearing aids in many places and on many occasions

Bone conduction speakers offer a technical base for hearing voices and sounds through bones. These devices enable hearing-impaired people to catch sounds when there is no vibration in the air, and operate on the principle that we perceive sounds when vibrations reach our hearing organs directly. Based on this principle, we developed and patented a small, high-output bone conduction speaker that converts audio signals into vibrations. We realized unprecedented user convenience by integrating this speaker in a headset. 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 (Kikuchan), and a helmet-type communications system (Shellshocker). Please visit the home page introducing our products for details.