Recently, a large number of so-called completely, or truly wireless headphones, have appeared on the market, which are distinguished by the complete absence of wires and are two self-contained in-ear headphones without any wires between them. It looks impressive and makes an impression, especially if you see such a solution for the first time. Technology does not stand still, and the miniaturization of everything and everyone allows you to create devices that could previously only be seen in science fiction films. Battery life, sound quality (thanks to the introduction of new codecs and audio compression methods), functionality and capabilities are gradually increasing, and the idea that you can completely abandon wires is actively promoted by manufacturers who are removing the jack 3.5 connector from smartphones.
Most A-brands have already managed to present several generations of such devices, having filled the cones on the first versions and, thanks to this, finalizing the subsequent ones, taking into account the wishes of users. This did not always work out to the fullest, and most of these products did not become massive until the manufacturer came to the market, which is a locomotive that moves to the masses and makes popular what others could not promote – Apple with your AirPods. Despite the average sound quality and controversial ergonomics, these headphones are quite expensive for the average layman and have become very popular.
Among these headphones, there are both very budgetary devices from unnamed Chinese manufacturers, as well as rather expensive models from enthusiasts and large brands.
However, all of them are united by one nuance that calls into question the convenience of everyday use of such 'true-wireless ears' – sound delay.
Wireless headphones can have very high quality sound, with excellent detail and elaboration of all frequencies, deep juicy bass and accuracy. A prime example is my basic Apollo 7S headphones from Erato.
You really enjoy listening to music in them. But watching a video on Youtube becomes uncomfortable. No, the sound remains the same cool, rich and everything else, but the delay … The sound lags behind the picture for a split second, but this is enough to make viewing uncomfortable.
Faced with this phenomenon on my beloved 'ears', I wondered how other manufacturers were doing with this situation. And it turned out that the delay is everywhere. Here is a screenshot of the Bose forum where users are complaining about a similar issue.
And if we are talking about watching movies through any player, the problem can be solved by simply selecting the delay in the player settings so that the video sequence coincides with the sound. But in the Youtube I often use, this trick did not work. After experimenting a bit, I found out that there is a delay only when using both headphones at the same time. If you disable one of them, the delay disappears and the sound is synchronized with the video.
We can conclude that the point is how the sound is transmitted to both headphones. A short 'googling' gave an answer to this too:
In so-called 'true wireless' headphones, instead of one Bluetooth, two receivers are used, which means that the data must be transmitted twice, which can cause problems with audio latency during video playback. This is due to the fact that such headphones need additional time (20 to 80 milliseconds (ms)) for buffering to prevent signal dropout between the headphones. This leads to a delay in the sound.
The implementation scheme can be different. When turned on, one of the headphones takes over the role of the main device and acts as a signal repeater to the second earpiece. In this case, the signal must be received, processed and then transmitted to the second device. It all takes time. Given the relatively small latency, this is not noticeable when listening to music. But when watching a video, a lack of technology emerges – the video is played faster, and the sound is lagging. It may be that both headphones are receivers at the same time. In this case, the source (your smartphone) transmits the signal simultaneously to two headphones, doing it in portions and alternating them with each other. It is precisely this alternation that takes precious milliseconds, by which the sound is delayed relative to the picture.
At the moment, this is a massive problem common to all manufacturers of such devices. It can be solved, and the solutions can be different. You can, of course, wait for the next breakthrough in the principle of sound transmission and the creation of such a transmitter that can drive two independent streams, synchronizing them in real time with each other. And you can do it easier – to implement a way in which a smartphone or tablet will clearly understand which device is connected to it, so that you can simply synchronize audio and video at the software level, adding a similar delay in video playback. But this requires that accessory manufacturers work closely with smartphone manufacturers and add support for such interactions to their devices.
It is much easier to implement this if the manufacturer of both smartphones and similar accessories is the same vendor. This is also supported by the fact that when using AirPods on iPhone with OS version 11.2.6 and higher, the delay is minimal and almost imperceptible, but if you use the same AirPods on other devices, the delay becomes uncomfortable.
The situation is exactly the same with Samsung devices – Gear IconX 2018 paired with Samsung Galaxy S9 allows you to watch videos without noticing the delay, but when you connect the same headphones to another phone, you won't be able to watch comfortably – the delay will again be noticeable.
Apparently, at the moment, the whole problem is to add support for different wireless devices at the driver level in smartphones, creating a kind of universal driver or add-on that will allow gadgets from different manufacturers to work correctly.
Today the situation is such that the manufacturers of the best in terms of sound quality 'true wireless' headphones are companies that do not make smartphones. For this reason, they do not have the ability to implement interaction with smartphones at the level of hardware and drivers, and they are forced to be content with universal solutions. When thinking of buying a 'true wireless' headphone, keep this feature in mind and project it into your use case. If we are talking about listening to music, and only music, then this will not affect your feelings in any way, and it will be possible to select headphones solely for the sound quality and fit. If you absolutely need to watch videos and need a 'true wireless' device, your choice is significantly reduced to just a few models that will work correctly only with the same limited list of smartphones.
Given the increased interest of the industry in wireless technologies, we can only hope that in the near future this issue will become urgent for most manufacturers of both smartphones and portable equipment, and within the framework of cooperation they will find an acceptable solution that will suit everyone. All music and fewer wires.