Bone-Conduction Headphones: Are They Right for You?
Bone-conduction headphones offer athletes who like to work out to music an alternative to traditional earbuds or the sometimes-bulky over-the-ear headphones. How do they work though? And what are the pros and cons of using them? Read on to find out.
How Bone Conduction Works
Sound waves travel through the air and then through several parts of the ear before they reach the eardrum. The sound waves cause the eardrum to vibrate, which in turn, causes the three small bones— you probably remember them as the hammer, anvil, and stirrup— attached to the eardrum to transmit the vibrations to the cochlea. The cochlea converts the vibrations into electrical impulses, which are then sent to the brain via the auditory nerve.
That is only one way our brain processes sound, however. The brain can also process sound waves that travel through the bones of the head. When sound waves cause the bones of the head to vibrate, they are transmitted to the cochlea, which sends electrical impulses through the auditory nerve, just as if the sound waves had traveled through the ear. This mode of sound transmission is called bone conduction.
Composer Ludwig Van Beethoven may be the father of bone-conduction headphones. To accommodate for his hearing loss, he attached a rod to his piano, which he then connected to his head. The sound waves from the piano were transmitted via the rod to the bones in his head, then to the cochlea and finally to the brain as music. This concept is the current basis for the technology behind bone-conduction headphones.
Bone-Conduction Use for the Hearing Impaired
The use of bone-conduction technology has greatly impacted those with hearing loss and the medical profession that treats it.
Although cochlear implants for the hearing impaired have been extremely successful, the implants rely on air conduction of sound waves and the ability of those waves to pass through to the inner ear. For those patients with damaged or impassable middle ear canals, those sound waves could never reach the inner ear, making a cochlear implant useless.
But, bone-anchored hearing aids (BAHA), which are based on bone-conduction principles, have given those with hearing impairments another option.
In a BAHA system, a small sound processor is attached to a titanium base, which is implanted in the bone behind the ear. Once the sound processor is activated, it operates almost the same way as a conventional hearing aid but instead of sending sound waves through the ear canal, the vibrations are sent via the skull bones to the cochlea.
Bone-Conduction Headphones: Pros and Cons
Bone-conduction headphones began showing up on the market in the early 2000s. Currently, there are a variety of brands being manufactured at a wide range of price points—starting as low as $25 to more than $150.
For those who struggle with earbuds not fitting well and continually falling out during exercise, bone-conducting headphones may offer a better, more stay-put option. Many models have a section that is worn over the ear, which adds an extra point of stability.
In addition, bone-conduction headphones keep the ear canal free to transmit ambient noise, critical if you are running or biking on a busy road and need to monitor oncoming traffic for safety reasons. Bone-conduction headphones also offer drivers the ability to use headphones legally as they don’t interfere with the auditory awareness necessary for safe driving.
A point of contention for those in the audiology field is whether bone-conduction headphones protect the ear from hearing loss that some associate with earbud use. Some consider bone-conduction technology very safe and that they even protect the ear from harm due to excess noise, which can irreversibly damage cochlear cells and lead to hearing loss. Others argue that, despite bone-conduction headphones not being fitted into the ear canal, the process by which the sound waves are transmitted—via the bone versus via the ear canal—still has the same impact on the cochlea and so can also lead to damage of the cochlear cells and thus hearing loss.
It appears that the biggest issue with consumers regarding bone-conduction headphones is sound quality and cost. Some of the early models were restricted by high cost and low quality, which made for limited appeal among those for whom sound quality was the paramount issue.
According to Aftershokz CEO Bruce Borenstein, in an interview on cnn.com, “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,” he explained. Borenstein further notes that his company’s introduction of dual transponders has increased the frequency of vibrations, which in turn, has improved sound quality.
As improvements such as this are brought to the market, expect to see the quality of sound from bone-conduction headphones to continue to improve.