Hello!
As an avid cyclist and music lover at the same time, I have long been looking for an opportunity to combine listening to music with cycling without compromising safety.
The options tested included a wide variety of audio devices, ranging from wired earbuds to wireless earbuds that broadcast ambient sounds inward using dedicated microphones. In addition, there was an attempt to use an external speaker, but in this case the sound just blows away at high speeds, and the need to listen to the music is more tiring than pleasurable. As a result, none of these options covered the entire spectrum of requirements.
In the process of trials and tests, I remembered that once upon a time I came across a mono-headset, which had neither a speaker nor a reinforcing emitter, and the sound transmitted through the bones of the skull. Unfortunately, years ago (it was this year in 2011), I can't remember which manufacturer the device was, but it doesn't matter. The very fact that there are such devices is important, and should come close to my requirements. Remembering this, I thought that since then, probably, many people have decided to work on improving such an unusual and revolutionary technology.
Imagine my surprise when the search returned only a few companies that are closely involved in the development of consumer electronics based on this technology.
Why? Is it really difficult to produce such devices?
In order to understand why there are few such devices on the market, let's try to find out what they are.
The technology behind these devices uses a phenomenon called bone conduction. Here's what Wikipedia tells us about it: Bone conduction is the transmission of sound to the inner ear through the bones of the skull. Through bone conduction, sound can be perceived by people with both normal and impaired hearing.
Given the unusual operation of such devices, it may seem that the effect was discovered quite recently and simply not yet sufficiently studied. However, as it turned out, this is not at all true.
The first hearing aid using bone conduction technology was described in 1923 by Hugo Gernsback under the name 'Osophone'. Just think, in 1923. The beginning of the 20th century!
Since then, such devices have been actively used in medicine and the army, but somehow it did not reach consumer electronics.
But why?
Bone conduction of sound
Let's try to figure out what is bone conduction of sound?
To begin with, let's remember what sound is.
Sound is a physical phenomenon, which is the propagation of mechanical vibrations in the form of elastic waves in a solid, liquid or gaseous medium.
A person has two types of ways to perceive sound:
- Air conduction of sound.
- Bone conduction of sound.
Most often, we are faced with the first method – the perception of sound in the form of vibrations in a gaseous medium (in air), which are perceived by our hearing aid, which essentially consists of three main parts: the outer ear, the middle ear and the inner one.
In the case of air conduction, sound entering the outer ear causes vibrations of the tympanic membrane, which are transmitted to the malleus, incus and stapes, the displacement of which causes the main membrane of the cochlea to vibrate.
But in fact, sound travels best in solid environments.
Bone conduction, in contrast to air conduction, is the transmission of sound vibrations directly to the inner ear, through the hard bones of the skull, bypassing the outer and middle ear.
In this case, sound waves are decoded into vibration. Then the vibration of the bones of the skull is transmitted to the stirrup, and finally the excitation of the receptor occurs due to the vibration of the stirrup (osteotympanic pathway).
Obviously, to transmit sound in this way, the sound source must be in contact with the skull bone.
Most often, piezo emitters are used as a sound source for such devices. A piezo emitter is an electroacoustic device capable of reproducing sound due to the inverse piezoelectric effect.
I first encountered such a radiator when I was 10 years old. My parents gave me a Montana watch with 16 melodies. Remember those?
It was extremely interesting how this watch reproduces sound.
Naturally, I opened my watch. On the inside of the lid was a strange brass plate with a white bulge in the middle.
Tests have shown that the watch cannot play without this plate. Imagine my surprise when I, having decided to connect two wires from the radio to the plate, heard the music that was broadcast by the radio 'Mayak' at that moment.
Actually it was the same piezoelectric emitter.
However, I repeat that until relatively recently, the main consumer of such sound transmission systems was medicine and the army. Hearing aids or communication systems.
The advantages of the technology are obvious:
- Safety. The device does not cover the ears, which means it does not cut off the user from the outside world.
- Versatility. Thanks to the principles of work, music can be listened to even under water.
- Wow effect. Unusual technology clearly attracts the views and interest of others.
Despite this, at the moment, only a few companies are seriously engaged in the production of such devices.
Manufacturers
Let's see what these companies are and what devices they offer us.
The leader can be called Aftershokz, which, before entering the consumer electronics market, worked very closely and fruitfully with the military, producing communications equipment for them.
Among the models of this company, one can distinguish Trekz Titanium, which is a wireless headset that allows you to listen to music and talk on the phone while hearing ambient sounds, and Trekz Titanium mini, a smaller version with an identical design and different dimensions.
A more compact wireless model, Bluez 2S, also suitable for women.
As well as wired Sportz Titanium headphones.
And a version with a microphone with an unpretentious name Sportz Titanium withmic.
For a long time Aftershokz were actually monopolists in this market, and they had time to develop this direction and feel confident in this niche.
This was, in fact, until 2015, when two more companies announced themselves loudly, about to compete for their piece of the pie.
These were the DigiCare company, which presented its development at CES-2015 under the uncomplicated name DigiCare Do, and Studio Banana Things (yes, these are the guys who invented the pillow that can be put on the head) 
in the same year, 2015, launched on Kickstarter, eventually successfully completed, raising funds for the production of its headset called BATBAND.
And if DigiCare, previously repeatedly seen in plagiarism, this time also did not do without borrowing (very much their typeface is similar to the Aftershokz product).
Then Studio Banana Things showed a device with a distinctive, interesting design.
Rombica offers inexpensive solutions.
For example, model FIT X-01
In addition to these four companies, a whole host of Chinese manufacturers have appeared, producing similar solutions. However, I would not dare to buy them – I am alarmed by the fact that some of these companies, before the production of the bone conduction headset, produced … rubber gloves.
So, leaving aside the nameless Chinese, who most often simply try to copy Aftershokz products, there is not much room for maneuver.
Conclusion
Why hasn't such a remarkable, at first glance, technology been widely adopted in consumer electronics along with the usual speakers?
It is difficult to answer this question unambiguously.
Among the reasons are usually called the limited frequency range that such devices can transmit, as well as the consumer's wary attitude towards the systems that make the bones of the skull vibrate, since many have heard that constant vibrations are not very beneficial for the body.
It is only a stretch to agree with the first statement, as Aftershokz claim that the reproducible frequency range in their latest models does not differ from that of traditional systems with dynamic radiators.
Second, rather a stereotype, since the harm of such vibrations, firstly, has not been proven, and secondly, they are certainly not more harmful to hearing than dynamic emitters thrust into your ear and tormenting your eardrum.
Among the objective disadvantages that arise from the features of the technology, one can single out the need for constant close contact between the device and the user's head in order to obtain high-quality sound, which may cause discomfort for some due to pressure.
In addition, the disadvantages include the presence of tangible vibrations, to which not everyone can get used to.
That is, perhaps, all that can be blamed on such devices.
In the very near future, I intend to test all these statements on myself, using a headset with bone conduction technology. You can read about the results of this testing on the pages of android.