The height of spring! The grass is blue, the birds are barking ... Motorcyclists and cyclists crawled out of the garages. As an amateur, it is impressive to dissect the city streets on your chopper, so go on a bike ride on the pedal transport, I’m worried about two things - safety and comfort. And in the matter of listening to music, these two points often conflict with each other.
You can ride a bike with earplugs, but not for long ...
You can put the audio system on a motorcycle, but such a custom can greatly spoil the appearance of the bike, and others may not like your chosen repertoire.
But here the guys from Medgadzhets suggested that I try a compromise solution - Aftershokz Trekz Titanium bone conduction headphones.
Inspection
Headphones come in a stylish small box with a transparent cover.
Figure 1: Box Content
Inside the box is a gentleman's set:
- Actually, the headphones themselves;
- USB-microUSB cable for battery charging;
- Headphone storage bag. Probably waterproof, or at least slowing down the rate of wetting;
- Ear plugs for listening to music in noisy places;
- Some amount of waste paper.
Headphones are lightweight and compact. So flexible that you can tie them in a knot and they will have nothing.
Figure 2: Emitters and controls
Wireless headphones (Bluetooth 4.1), inside the battery for 7 hours of continuous operation. On one handle there is a microUSB connector for charging, as well as volume control buttons.
The emitters themselves in the vicinity have a convex part that directly touches the bone, as well as a series of holes, which, according to the manufacturer , help reduce LeakSlayer sound leakage.
One of the emitters has a button for answering calls - it is also a headset with a microphone.
Bone conduction
The sound is an elastic wave and it is not surprising that it spreads in elastic media, namely in air, liquid and solid objects. And what is the bone is not a hard object?
I think many people know the effect of pipe conduction, when a madman knocks on a pipe on the first floor, and he hears the entire riser.
Figure 3. Ear structure
The design of our hearing aid is interesting because the inner ear, on the one hand, perceives air vibrations through the eardrum, and on the other hand, it is completely unprotected from the vibrations of the case in which the skull is located.
As a result, headphones using the effect of bone conduction, being pressed to the temporal bone, transmit vibrations to the inner ear through the "hard channel".
Here are several features at once:
- The earpiece should be tightly pressed to the bone.
- The auditory canal remains open.
- The bone is porous. And porous materials absorb sound well.
Comfort
To transmit oscillations of the radiator to the bone, the headphones must exert substantial pressure on the temporal region. Essential, but not critical. Yes, the headphones are felt, but two hours before work go unnoticed, and after you take them off - there is no particular relief, since they do not bring discomfort.
Noise
Figure 4: Headphone Arrangement on the Ear
As can be seen the ear canal remains open. From here - features of operation of earphones in noisy places.
The inner ear had two sources of signal - external, through the vibrations of air, and internal, through the vibrations of the bone. The question is who will transmit whom?
I tested several use cases and came to the following conclusions:
- Walking and jogging is a great option, as is cycling. Street noise goes into the background, but it remains possible to hear what is happening. The horn and squealing brakes of the car will definitely be heard.
- Public transport: in the ground, external sounds do not interfere, but in the subway the environment is so noisy that as soon as the train starts moving, the music is completely inaudible.
- Riding a motorcycle - it all depends on the volume of the engine of your iron horse. V-Twin for 650 cubes, for example, does not tolerate competition. In a motorcycle helmet, by the way, the headphones themselves do not interfere, but the handle touches the jacket collar a little. But on sports motorcycles, I would not even ride in these headphones - the price of abstract attention here is too high.
Figure 5: Volodya would be happy to ride with the wind, but he has no hands. All that remains is to pose for the camera.
Headphones sound good sound outside. On the street or in the bus, hardly anyone will hear your music, but the colleague sitting at the next table is very much.
Sound
When I put on my headphones for the first time and turned on Ozzy Osbourne ... well ... well ... I remember in the Realtech driver there was such a sound effect “pipe” ...
- Bass - rather weak. They are there, but the bass player is tired and plays at half strength.
- Top - blunted. As if violinists and pianists settled behind a thick curtain.
Fans of rock and metal will be puzzled.
I suppose that a lining in the form of skin, and a porous bone, plays a significant role. If, for example, to clamp the earpiece between the teeth - then immediately appear top. Although the bass and the middle, on the contrary - fail. But few people will listen to music with an earpiece in their mouths. Firstly, it is inconvenient, and secondly - the headphones are never waterproof. IP55 is protection from dust and jets of any direction, they should not be immersed in liquid.
In other words, having received a significant advantage - the ability to listen to music and hear others, we condemn ourselves to limit the repertoire. ZZ Top, Beatles, Gary Newman, David Bowie and some others sound well from their personal preferences in these headphones.
Tests
I decided to conduct a series of measurements related to target and spurious emission of sound. When compared with conventional earbuds, how big is the difference between headphones that are at a distance from the ear and tight to it?
To do this, I took my microphone, put a fresh battery in it and connected it directly to the oscilloscope.
Figure 6: In the right corner of the ring, high-quality wired earplugs with silicone inserts removed, in the left - our wireless headphones.
To begin with, place the headphones at a distance of a couple of millimeters from the microphone and measure the amplitude of the signal. We set the volume so that the amplitude for both headphones is the same.
For headphones, gags is a normal mode of operation. It is noteworthy that for equalizing amplitudes up to 2 mV for Trekz Titanium volume was 100%, for plugs - 80%.
Figure 7: Waveforms of headphones held at a distance of 1mm from the microphone. Trekz Titanium on the left, gags on the right
Now we press the headphones close to the microphone and look at the result.
Figure 8: Oscillograms of headphones, closely pressed by emitters to the microphone. Left - Trekz Titanium - 24mV, on the right - gags, 5mV
The gags gained only 2 times the weight (pay attention to the division prices on each oscillogram - 10mV / div and 5mV / div), but the amplitude of the bone headphones has increased 12 times! If a normal earpiece is attached to the back of the head, or clamped between the teeth, then a miracle will not happen either. Still, the bone's trick is that it is not the case of the headphones that is pressed against the temple, but the radiating element itself.
Figure 9: We press the emitter to the microphone body outside the receiving windows
Let's try to put the earpiece on the side of the microphone to minimize airborne sound transmission. My microphone is pretty high quality and sensitive element inside is in limbo, but even in this case, it picks up the vibrations of the case.
Figure 10: Headset pressed to the side of the microphone. Amplitude 4mV
At the very last moment, I thought - what if I leaned the headset with the back side? This will show the directivity of the radiation and the level of spurious sound.
Figure 11: Headset back to microphone. At the left - at a distance of 1 mm (the same 2 mV), on the right - pressed. 5mV
From the oscillogram, you can make a clear conclusion - the target sound clearly comes from the emitter and nowhere else, and the parasitic one is not much different from the gags. But! Plugs with silicone insert will not release sound from the ear. But the usual liners - quite a. And the music of them just heard.
I will sum up
I have a double impression of headphones. I will definitely take them with me to the 100-kilometer bike ride, but I will continue to go to work without musical accompaniment - I use too noisy vehicles. But I don't want to use earplugs either. I do not run, so I can’t say anything here. I have no special complaints about the sound quality, but I agree, it has its own characteristics and not everyone can like it.
If you decide to take it, then when you buy headphones on the Medgadzhets site on the coupon TREKZ25, they promise a 25% discount until May 9. A good option, taking into account not the smallest price for a gadget.