Is Bluetooth audiophile sound possible? We looked at it.

High-resolution audio and lossless streaming are becoming mainstream through services like Amazon, Spotify, and Apple Music, making quality sound more accessible than ever. But wireless headphones and speakers were left out, thanks to Bluetooth’s ho-hum audio. Step into Qualcomm’s brand new aptX Lossless codec – the firmware that processes, transmits and receives digital audio from source to listening device – and you have a potential game changer for streaming audio from these services via Bluetooth without loss of fidelity. The potential of Bluetooth audiophile sound is eagerly awaited news, but for now you’ll have to settle for CD-quality (16-bit / 24kHz) sound, and if you’re using Apple and / or Beats hardware, they use a proprietary codec and have not yet announced hardware support.

What about the sea of ​​truly high-resolution recordings made at 24-bit / 96kHz, which are better than CD quality? These are still irrelevant for Bluetooth, but the speed at which the technology has evolved seems to indicate that we are only a generation or two of codecs away from this type of high-resolution audio support.

aptX Lossless always relies on great hardware to reproduce audio, which means the Bluetooth experience will only always be as good as the weakest link in the chain. Let’s take a look at what is needed to create a satisfying end-to-end digital audiophile experience.

aptX lossless from Qualcomm The codec aims to make Bluetooth a viable option for digital audiophiles who want CD-quality wireless sound. How far that goes depends not only on how many, but on which companies adopt it, as well as whether discerning listeners will deliver on the promise of even higher resolution sound down the line.

Source

First of all, let’s talk about some lingo. Sample rate refers to the number of digital “slices” that make up each sound in the recording; more slices means more detail, at least up to a point. Bit depth represents the amount of information contained in each slice and is often used interchangeably with resolution. CD quality is 16-bit / 44.1kHz, while “high-resolution” audio is considered 24-bit / 48kHz and above. It’s a good rule of thumb that acoustic genres like classical, jazz, and folk tend to have a wider range between loud and soft sounds than most rock, pop and electronic music, and benefit greater bit depth.

The only way to get CD-quality (and higher) sound through Bluetooth’s narrow wireless “channel” without losing fidelity is to overwrite it using lossless compression. Remove data such as frequencies outside the average human hearing range, as well as those that are not generally reproduced well by most consumer headphones or speakers, and the resulting “lossy” file is smaller, but suffers from poor, thin bass detail and distortion in high frequency sounds like cymbal crashes. Lossless compression codecs are much more selective about what to delete, so the files are not as small but with no audible difference from the original uncompressed file (huge). Lossless files and streams can support 24-bit / 192kHz and above, depending on the format, but we’ll have to wait some time for Bluetooth to support this kind of resolution.

The transmission

Codecs are the firmware that compresses, transmits, receives, and decompresses digital audio between devices. There are several on the market, including Sony’s LDAC and Apple’s AAC, but Qualcomm’s aptX HD (introduced in 2016) has become widely adopted and offers great sound (but still “lossy”). ). aptX Adaptive arrived in 2018 and added the ability to transmit even more data with more efficient (but still “lossy”) compression and higher fidelity. In September 2021, Qualcomm announced that it include a Bluetooth Lossless codec in its Snapdragon audio chipset, which will allow the transmission of CD-quality sound from smartphones to wireless headphones.

The result

The bottom line is that to reap the benefits of all lossless content, listeners comfortable with CD quality will need a smartphone and headphones that support the latest aptX Lossless codec. And it is better if these headphones are of high enough quality that they can reproduce audio with exceptional clarity. If the smartphone has aptX Lossless integrated, but the headphones are still stuck on aptX Adaptive or aptX HD, you lose audio quality. If your headphones support the latest codec but have inexpensive manufacturing audio drivers, you are losing audio quality. The same will apply to aptX Lossless compatible speakers and home A / V components when they are finally available.

The market

aptX Lossless is currently limited to a handful of Android phones from Motorola and Xiaomi, as well as a few unsatisfactory-looking sets of wireless headphones. Apple devices like iPads, AirPods, and Beats are still stuck in the era of “loss”, and Apple’s wireless protocol, called AirPlay, which supports lossless streaming over Wi-Fi, is not suitable for the low power requirements of wireless headphones. High-end audio hardware makers like Bowers & Wilkins and Bang & Olufsen who have already tapped into the Bluetooth audio pool are still catching up with the latest round of Bluetooth updates, with nothing newer than aptX Adaptive. Bose is another notable absence from the aptX Lossless scene.

Ultimately, if aptX Lossless turns out to have reasonably consistent audio quality and finds its way into good enough hardware, we could see a boom in high-end wireless audio in 2022. It’s also possible that some companies that cater to audiophiles who demand better – CD quality covers their bets and expects Bluetooth to be able to handle high-resolution (24-bit / 192kHz) audio – which seems likely within the next couple of years.