During Panasonic's CES 2013 press conference, the company announced that it was debuting a new pair of headphones, which use bone-conduction technology. If you follow the headphone industry, then you may already know a bit about this technology; companies like Madcatz, Audio Bone, and AfterShokz have offered bone-conduction headphones for the past few years. But Panasonic's announcement of the RP-BTGS10 headphones (due out this fall) marked the first time I can recall one of the big-name manufacturers embracing the technology. Now we're hearing reports that Google might enter the fray; there's speculation that the much-anticipated Google Glass virtual-reality headset may use bone conduction. So what is it?
Just as the name implies, bone conduction transmits sound waves through the bones in your skull. The vibrations reach the cochlea, or inner ear, which converts them to electrical impulses that travel the auditory nerve to the brain. The technology itself is not new. Perhaps one of the earliest pioneers was Beethoven, who would bite a special rod that was connected to his piano in order to transmit sound vibrations through his jawbone. Inventors dating back to the early 1900s have used the technology in telephones and hearing aids.
Anyone remember the Bone Fone, introduced back in the 1970s? It was a radio that hung around your neck and used bone conduction to send sound waves to your inner ear via your neck, shoulders and chest. The sound quality was apparently pretty poor, and the product was soon killed by the Sony Walkman. However, the concept lived on, the research and development continued, and now we're seeing a growing number of bone-conduction headphones, sometimes called bonephones. These headphone designs usually wrap around the back of your head, come over your ears, and rest on the bones near your ear - sometimes on the cheekbone just in front of your ear. As Audio Bone describes how they work, the headphones "perform the role of your eardrums," decoding the sound waves and converting them into vibrations.
Bone-conduction technology is often employed by the military so that soldiers can receive commands through headsets while still being able to hear what's going on around them, which is obviously of critical importance in combat. That same philosophy of safety is one of the primary marketing approaches for consumer-oriented BC headphones. Bone conduction is essentially the opposite of noise cancellation. These headphones are designed for people who want to be able to listen to music while still hearing the sounds around them: joggers, bikers, hikers and other outdoor enthusiasts who need to be aware of their surroundings and to hear cars, sirens, and other audible dangers.
The open-ear design can also be beneficial in an office environment, if you like to casually listen to music throughout the day without disturbing others, but still need to hear a ringing phone (or a yelling boss). As a mom, when I do have a moment to listen to music or podcasts through my iPhone, I generally only wear one earbud so that I can remain fully aware of what's going on in the house; bone-conduction headphones provide an alternative solution.
Read on to Page 2 to hear about hands-on time with bone conduction headphones . . .
Speaking of volume level, one interesting topic that has arisen regarding bone-conduction headphones is whether or not this approach has any benefits in terms of preventing hearing damage. Studies consistently show that listening to music at loud volumes for extended periods of time through headphones can damage your hearing; an article from the American Osteopathic Association states that one out of five teens has some form of hearing loss, a rate "30 percent higher than it was in the 1980s and 1990s". AfterShokz mentioned in one of its early press releases that, since the BC approach bypasses your eardrum, there's no risk of eardrum damage. That may be true, but eardrum damage is generally not the culprit in noise-related hearing damage; the real culprit is damage to tiny hair cells in the inner ear that get overworked and eventually die. These cells can be overworked by BC headphones just as much as any other earbud or headphone, but there is an argument to be made that this type of headphone doesn't encourage you to play your music at ridiculously loud levels to shut out the world. If you embrace the open-ear approach, then you likely embrace the idea that your music is meant to be ambient and not engulfing.
Suffice it to say, bone-conduction technology is not targeted at the audiophile. Don't expect to be immersed in a spatial soundfield with pristine imaging and full-range sound. Bass response was quite lean, but higher-frequency reproduction was solid. Vocal clarity was very good, which made the BC headphones a good choice for listening to podcasts or for use as a headset with my phone (the Sportz M2 have an in-line controller/microphone). Because you can hear audio coming from the headphones before you put them on (just like any other headphone), you may find yourself wondering, as I did, how much of the sound is simply entering your ear in the traditional manner. Put your fingers in your ears, and the sound actually gets a bit louder and fuller, with more bass response. Of course, that defeats the purpose of the open-ear design, but it was an interesting experiment. If you put the BC headphones directly over your ears like a standard on-ear headphone, the high frequencies fall apart, becoming tinny and echoic.
I don't really see bone-conduction headphones making a huge wave in the more audiophile-oriented space that we often cover here at HomeTheaterReview.com, but they make a lot of sense out there in the real world for everyday headphone listening ... especially if you value your safety as much as your music.