Audio via bluetooth is getting better and better. Not only is it possible to send audio from a greater distance to a speaker or headphones, the quality is also getting better. A term that we often see coming back is aptX, which allows music to be transferred in better quality. But what is aptX, and what's behind it?
By default, bluetooth uses the codec SBC to package audio and send it to a speaker or headphones. SBC stands for Sub Band Codec and has been used since the introduction of bluetooth. However, according to Johnny McClintock, manager of aptX sales and marketing at Qualcomm, SBC was intended to keep the bitrate of the music as low as possible, which improves the connection, but certainly does not improve the music quality. “The result is a bitrate of barely 200kbps,” said McClintock. “As a result, almost all tones above 16kHz are lost when audio is sent via SBC.”
When it became possible to send more data via bluetooth, Qualcomm brought the codec aptX to the world of bluetooth. The concept of aptX dates back to the 1980s, where it was used to transmit audio over the Internet with minimal loss of quality. The codec as we use it today in bluetooth was introduced in 2008. Unlike the barely 200 kilobytes per second used by SBC, audio can be sent at 354 kilobytes per second using aptX. With aptX it is possible to play audio files of CD quality, while also sounding largely CD quality.
Fine, better, best
Two variants of aptX have now been launched on the market, aptX Low Latency and aptX HD. The former distinguishes itself by limiting the delay between the source and the sound in the headphones to no more than 40 milliseconds. In comparison: with SBC there is usually a delay of roughly 220 milliseconds. Especially when playing video and playing games, it is important that the sound of the screen is synchronized with the sound of your wireless headphones or speaker. With aptX HD it is possible to play music with the high resolution of 24-bit/48kHz. There is still compression, but with aptX HD it has been reduced to the minimum. With aptX and all variants, the rule applies: both devices must support it.
An improvement in sound quality can of course never hurt, but there is no guarantee that you will always hear the difference. As we said, with aptX it is possible to make music sound like CD quality, but to do that you also have to play music of CD quality or higher.
You won't notice much difference with a simple MP3 file on Spotify. Such music files are already heavily compressed, so that many details in the music - especially in the higher and low frequencies - are quickly lost. Music of CD quality or higher still contains many of these details and therefore comes into its own with aptX.
Do you have a smartphone with aptX, high-quality music and headphones or speaker with aptX? Then it is a pleasure for the music lover. Finally you can enjoy music in CD quality wirelessly.