Picture this, you have an important business meeting you need to attend but your favourite football team are about to kick off in the cup final, what do you do? Bone conduction could be the answer, but how is this possible?
We hear sounds from both our bones and our internal eardrums. We mostly hear through air conduction, where our eardrums convert sound waves into vibrations, which are then transmitted to the cochlea (inner ear). In some cases, we hear vibrations directly to the inner ear, effectively bypassing our eardrums, and is one of the ways we hear our own voice.
However, we also hear through elements of bone conduction too! Ludwig van Beethoven, the famous 18th century composer, discovered this phenomenon and used it to his advantage. At the time he was almost completely deaf, yet despite this he found a way to hear the sound of his piano through his jawbone. He attached a rod to his piano and clenched it tightly with his teeth. This method meant he could interpret the sound as vibrations were transferred from the piano to his jaw. This has proven that sound can reach your auditory system through another medium besides eardrums: bones.
Today, we use this mechanism for many applications. From a medical point of view, it is used to make people with hearing difficulties caused by eardrums damage, to be able to hear clearly again. As long as their cochlea is in normal condition, bone conduction will work.
Many new devices use bone conduction too: the speaker system from SGNL (http://www.mysgnl.com/) allows you to hear sound from your finger; Google Glass also uses bone conduction speakers, and modern headphones take advantage of this technology too.
For example, during the recent FIFA World Cup, you may have felt tempted to use a Football Pen device. This is a radio device installed within a regular ballpoint pen that uses bone conduction technology to create sound. As soon as the pen touches the jawbone, it transmits sound to users the inner ear, ensuring you the only person who can hear it. Therefore, you will be able to listen to the game while attending work meetings, just remember not to cheer too loudly when your favourite team scores!
Matthieu, Consultant, Leyton France
 “Google Glass uses human skull to transmit sound”, The Telegraph, 03 Feb 2013
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