AptX is an efficient bit-rate technology that promises to improve the performance of Bluetooth. To be certain, Bluetooth technology has the effect of teaching the sound quality that if you were using a wired product, you could normally receive. Due to its potential for far higher quality compared to the stock Bluetooth transmission, aptX got a lot of attention in the early days of Bluetooth. Low-power wireless transmissions that are designed to allow a connection between the headphones and another device such as a smartphone has a range of up to about 30 feet that allow you to hear through wireless headphones through Bluetooth. It also has limited bandwidth as Bluetooth requires low power, although it has gotten better as it has been enhanced. The initial version of aptX is still around, and is quite prevalent. The greatest improvement over SBC is that it requires a 384 Kbps bit rate. Between aptX at 384 and SBC at 345, there won’t be much, if any, audible difference. If SBC does not run at its best bit rate on one or more of your devices, but offers aptX, then you might hear an improvement. Providing 24-bit audio at a bit rate of up to 576 Kbps, aptX HD goes a step further, while the new aptX adaptive theoretically offers aptX HD sound quality at a lower bit rate and has the option of a 96 kHz sampling rate. Of note, there are no Apple products with aptX technology. But, as well as numerous speakers and headphones, there are plenty of Samsung, LG, Google and other phones. The list does not seem to be regularly updated, so it is worth checking the specs page of the respective manufacturer if you don’t see your current device or one that you’re considering. The Qualcomm currently owns the aptX patents, makes big claims about its technology.
In the last decade, Bluetooth technology has come a long way, currently in its version 5 iteration. AptX isn’t the magic bullet it once appeared to be. That doesn’t mean that it’s not potentially helpful, just that it doesn’t necessarily has done a lot of audible enhancement. However it can have other advantages, so it’s certainly worth learning about.
Digital audio is a collection of samples of what a sound wave at a particular moment in time looks like. It is a series of snapshots instead of a steady wave of sound. A playback device can reconvert them back into a smooth sound wave with enough of these snapshots. Alternatively, its original goal was to transmit your voice through a phone call, while using as little processing power as possible. This is called Low Complexity SBC or Sub band Coding. Both devices that are used wirelessly must be at the same high level, because SBC levels are different, or you just get the maximum level of any device that is the lowest. For stereo, this 16-bit/44kHz CD rate equates to about 10 megabytes per minute or over a megabit per second. While that’s not a lot of information these days, between a portable device and Bluetooth headphones, it’s still a lot more than what’s easily transmitted. If you were to stream it, it would also chew through your mobile data. These codecs a compression/decompression portmanteau, remove what you theoretically can’t hear using a method called psycho acoustic modeling. This allows them to significantly reduce the size of the audio files or streams. For example, MP3s are often around 1MB per minute. This is a decrease of 10x, with a corresponding decrease in the size file.
The future of aptX and Bluetooth:
Some new versions of aptX are beginning to appear in products with the potential to be far more interesting. What I’m interested is Low Latency aptX. The limitations of Bluetooth data speeds still imply that, regardless of the codec, wireless can not offer fully fledged lossless quality, but that does not mean that the quality is not good enough. Bluetooth headphones, where the voices do not match mouth movements. This is caused by the additional processing required via Bluetooth to get the audio to your ears. Low latency decreases the time to around 40 ms from SBC’s 200-300 milliseconds. This should eliminate lip-sync problems effectively. If you listen to a low-quality audio stream, switching to aptX HD on inexpensive headphones will not magically give you better sound, to put it another way. As stated above, even SBC, most other music streaming services or most commercially available MP3s can have a higher bit rate than Spotify Premium intelligent application of Qualcomm’s split-band ADPCM means that few will be able to make any significant compromises. For those who demand the most from their music collection, Qualcomm’s aptX HD technology is certainly a much appreciated improvement in audio quality that makes Bluetooth a more viable platform than ever. Consider what you are listening to as well, and perhaps more importantly. On paper, with a high sample and bit rate, aptX HD seems excellent. However, unless you have a high-quality source, this extra capability is not important. Unless it has been restricted by a lower transmission type, a better transmission will not make your audio sound better. For example, Sony WH-CH700N noise canceling headphones have aptX HD.
In short, aptX HD is intended for those with a collection of music that is capable of making the most of their capabilities, and that certainly does not include everyone. There won’t be many advantages for those who prefer streaming music rather than carrying around a large FLAC library, or just looking to spend sub-$99 on a headset. AptX HD is a relatively new technology, which was announced back in January 2016, and is therefore not as widely available as its regular aptX counterpart, which can be found in some 70 percent of Android smartphones. Still, the technology is supported by a number of high-profile smartphones, and more will undoubtedly be underway in the future.
Can aptX offer better quality sound? Yes, usually a good thing is better compression, but it’s not a guarantee of good quality of sound. It’s one link in a chain, and the current link (SBC) functions perfectly well on most devices. The higher quality potential with aptX is not likely to be audible if you listen to all your music on YouTube and you’re happy with your free Spotify account. If you are trying to eke out the highest possible performance on some high-end equipment you already own, and you are looking for new audiophile tracks and new download solutions, aptX and aptX HD and Adaptive in particular may give you a slight bump over SBC. But if you’re that much of an audio quality sticker, I guess you’re listening to it all wired up anyway.