Skip to main content
Part of complete coverage on

Bone conduction: Get used to the voices in your head

<strong>Bone conduction technology</strong> allows people with deafness to hear, helps tech-heads talk, and lets swimmers listen to music underwater. <strong>Find out more.</strong> Bone conduction technology allows people with deafness to hear, helps tech-heads talk, and lets swimmers listen to music underwater. Find out more.
Hearing through your bones
Hearing through your bones
Hearing through your bones
Hearing through your bones
Hearing through your bones
Hearing through your bones
Hearing through your bones
Hearing through your bones
Hearing through your bones
  • Bone conduction technology is helping some people with hearing loss to hear again
  • But it could soon improve the lives of people with healthy hearing too
  • Google Glass uses it to communicate with users without blocking the ear
  • Talking pillows, safer headphones, and underwater music are all in the pipeline

(CNN) -- Long established as the premier portal for sound, your ears are facing increased competition from emerging techniques for transmission through your skeleton.

Bone conduction has rapidly become a critical asset for treatment of hearing loss. While a new generation of cochlear implants has had spectacular success in recent years, they rely on air conduction and the patient possessing a functional pathway from outer to inner ear. For patients with severely damaged pathways, such implants offer no solution.

Baha (bone anchored hearing aids) units work by passing sound from a microphone to a magnet or implant beneath a patient's skin, which is converted into vibrations in the skull and eventually arrives at the inner ear. This process extends the miracle of restored hearing to victims of such conditions as microtia or atresia, where the ear or canal is closed or deformed.

Making sea water drinkable

"It's the natural spectrum of sound compared with traditional hearing", says Brian Walshe, spokesperson of hearing treatment company Cochlear. "Even with amplification it's the same, there's no distortion."

The company recently launched a wireless Baha set, an indication of the technology's progress and growing popularity. Implants have become smaller and less invasive, while cosmetics have improved so that the system can be worn without advertising it.

Bone conduction is not a new discovery. Ludwig Van Beethoven overcame deafness by biting a metal rod attached to his piano to hear his work. Neither do they need to be compensation for disability - such systems have been used by military in environments that require awareness as well as audio instructions. A member of the SEAL team which killed Osama Bin Laden wrote in his autobiography that bone conduction communication was critical to co-ordinating the raid.

Sound vibrations pass from the outer ear, through the eardrum to the cochlea, which transmits them to the brain as electrical signals.
Graphics: Inez Torre

The innovation is beginning to seep into consumer electronics. In the early 2000s, headphone sets appeared that played music via the user's bones, but the systems were hamstrung by high cost and low quality, with common complaints about muffled and distorted sound. The makers of Aftershokz believe they have solved those problems with a unit that retails for $79.

"The difficulty for bone conduction has been transmitting vibrations through bone with enough power for music, you need to be on the 20 - 20,000 Hz frequency range," says CEO Bruce Borenstein. "We have been able to power dual transducers with enough vibration to make the sound musical, which has been our big breakthrough."

A transducer is used to convert sound into bone vibrations that transmit directly to the cochlea and on to the brain, bypassing the outer ear and eardrum.
Graphics: Inez Torre

The bone conduction system offers key safety advantages over traditional earphones, by leaving the user's ears free so that they are not distracted from their environment. It is even possible to drive wearing them, as they comply with the legal requirement to be able to hear on the road. The Audiology Foundation of America have also supported the concept, stating that it causes less damage to the ears than ear buds.

A flood of competitors are entering the market and innovation is not limited to headphones. Google Glass are using bone conduction rather than ear buds for their speaker system, although there have been teething problems. Multiple patents are emerging for underwater and deep sea communication systems, and the technology has become cheap and accessible enough to be viable for novelty items such as talking pillows.

The field has even expanded to offer audio communications through diverse body parts including the teeth and eyes. "In theory you can hear from anywhere", says Dr. Sunil Puria, ear biomechanics expert at Stanford University. "Although practically there would be disruption by having to pass through soft tissue depending on the point of contact."

The technology has offered a new dimension to advertisers, with BBDO trialling a system on German trains that plays targeted messages to commuters as they lean against the window. The company claim a positive public reaction, and promise the concept will deliver social benefits through delivering announcements and emergency warnings. But the scheme has been controversial, with civil liberty activists arguing it is invasive and delivers content without consent.

The difficulty has been in transmitting vibrations through bone with enough power to be musical
Aftershokz CEO Bruce Borenstein

Dr. Puria foresees another ethical concern. "As it vibrates your skull to generate sound, others around you can also potentially hear a message sent to you, so there will be privacy issues. That's a problem that needs to be solved."

But he believes the major technological hurdles have been overcome. "There has been tremendous progress, from miniaturization, to wearable and wireless, so that we have reached the holy grail of not requiring earphones."

From medicine to entertainment, from reef diving to sleeping in our beds, we may have to get used to a whole new set of voices in our head.

Read more from Make, Create, Innovate:

Stealing from nature: Incredible new tech inspired by biology

Forget wearable tech, embeddable implants are already here

This 'Star Trek'-style molecular sensor fits in your hand, reads your food

Part of complete coverage on
updated 5:39 AM EDT, Fri August 8, 2014
Engineer Alan Bond has been developing a new concept for space travel for over 30 years -- and his creation is now on the verge of lift off.
updated 8:10 AM EDT, Fri July 25, 2014
Crumbling buildings, burnt-out PCs, and cracked screens -- a new generation of "self-healing" technologies could soon consign them to history.
updated 5:09 AM EDT, Tue June 24, 2014
Discover a dancing cactus field, basketball on the Hudson River, and mind-bending 3D projections on robotic screens.
updated 1:07 PM EDT, Fri May 23, 2014
Would you live there? Design student Peter Trimble says it's actually a surprisingly good idea.
updated 10:50 AM EDT, Wed May 14, 2014
Alpha Sphere
Singing Tesla coils, musical ice cream, vegetables on drums... and this ball? Find out how "hackers" have created a new generation of instruments.
updated 12:43 PM EDT, Wed May 28, 2014
Technology has long learned from nature, but now it's going micro. "Cellular biomimicry" sees designers take inspiration from plant and animal cells.
updated 1:08 PM EDT, Wed April 9, 2014
Forget wearable tech, embeddable implants are here. Learn more about the pioneers who are implanting devices into their bodies.
updated 6:26 AM EDT, Wed May 7, 2014
A visitor of the 'NEXT Berlin' conference tries out Google Glass, a wearable computer that responds to voice commands and displays information before your eyes. It is expected to go to market in late 2013.
We know how wearable tech can enhance our fitness lives but there's evidence that its most significant application is yet to come: the workplace.
updated 4:13 AM EDT, Thu April 10, 2014
Samsung's research unit announces new way to synthesize graphene, potentially opening the door to commercial production.
updated 8:15 AM EDT, Mon March 31, 2014
iRobot, creators of vacuuming robot Roomba reveal how they learned from secret experiments -- in space travel, minefields, and toys.
updated 12:23 PM EDT, Fri March 28, 2014
A light-bulb glowing in middle of a room with no wires attached. "It's the future," says Dr Katie Hall.
updated 11:26 AM EST, Mon March 3, 2014
Knee replacements that encourage cells to regrow could soon be manufactured -- by spiders. Find out how.
updated 9:03 AM EST, Fri February 14, 2014
Meet Chuck Hull: the humble American engineer who changed the world of manufacturing.
updated 9:48 AM EST, Thu February 6, 2014
The key to self-knowledge? Or just the return of the phony "mood ring"? Check out our top mood-sensing technology in development.