Welcome to ‘Kagoo Explains’ - a series of short articles de-mystifying some of the confusing terminology used to describe tech. Today we’re looking at bone conduction technology - a fascinating tech that allows you to hear without ears!
Standard headphones are effectively tiny speakers that direct sound waves into your ears, where they are detected and processed into electrical impulses the brain can understand. A very effective method to be sure, but there is an alternative method of ‘hearing’ sound known as ‘Bone Conduction’.
Our ability to hear comes from sound waves that emitted from anything making a sound, be it a sneeze or a guitar solo. These waves fly through the air until they reach our ears, where they travel down the ear canal until they hit the eardrum. This absorbs the waves and creates matching vibrations, which are then amplified by 3 tiny bones before being sent to a strange-shaped bone called the ‘cochlea’. The cochlea transforms the vibrations into electrical signals, and finally these signals are sent via the ‘auditory nerve’ to the brain to be interpreted as sounds.
As the name suggests, bone conduction works by conducting sound through the bone of the skull to the inner ear. Bone conduction happens naturally all the time: when you speak, you’re perceiving your voice because of vibrations through your skull, not via your ears. Bone conducts lower frequencies far better than higher frequencies, which is the reason your voice sounds different when you hear it recorded - your perception of your own voice will be deeper and ‘fuller’ when you speak, and more high-pitched when you listen back to it.
A historical example of bone conduction: Beethoven started to lose his hearing in his twenties, which is a bit of an impediment for a composer! However he discovered that if he mounted a rod on his piano, and held it between his teeth, the vibrations allowed him to hear the music!
Bone conduction headphones sit on the cheekbones, slightly below and in-front of the ear. This placement allows the transducer of the headphones to send vibrations directly to the part of the inner ear that usually receives the vibrations from the eardrum - 3 bones known as the ‘malleus’, ‘incus’, and ‘stapes’.
These amplify the vibrations and send them to the cochlea, where they are sent to the brain as usual. This method bypasses the ear canal & the eardrum entirely, allowing users to listen to music without blocking their ears!
Bone conduction technology was originally developed by the military, where the ability to retain situational awareness - being able to stay aware of everything around you - is crucial. However commercial bone conduction headphones have now been available for many years, and are advantageous in numerous situations.
First and foremost, the ability to keep your ears free means you retain situational awareness - this is especially helpful for outdoor runners, since they can listen to music without losing the ability to hear cars or potential hazards. The transducer used for the headphones is more easily made totally waterproof, which makes them far more suited to underwater use. This also helps prevent nasty conditions like ‘Swimmer’s Ear’.
Moreover, because they send sounds straight into the head, they are very helpful for situations with lots of background noise - such as industrial settings, or in motorbike helmets. Lastly this technology can help with certain types of hearing loss.
Bone conduction isn’t perfect though - unfortunately these headphones have significantly degraded audio quality compared to standard headphones. Secondly, because nothing is blocking the ear, it means there is no sound isolation - this is a double-edged sword, since you’ll be able to hear everything, whether you want to or not. You will be able to hear your music, but intrusive sounds may cause ‘audio masking’ - where sounds are perceived differently when heard simultaneously. Finally, bone conduction headphones can be more uncomfortable, since they have to be kept pressed to the skin.
Bone conduction is a fascinating technology, and has numerous real-world applications. If you’re a runner who doesn’t want to be isolated from the outside world, or work in situations where normal hearing is difficult, then a good pair of bone conducting headphones may be a worthwhile investment. If this has got you interested, we have you covered with the best bone conducting headphones around!