Audio via Bluetooth is getting 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, with which music can be transferred in better quality. But what is aptX, and what is actually behind it?
By default, Bluetooth uses the codec SBC to pack audio and send it to a speaker or headset. SBC stands for Sub Band Codec and has been used since the introduction of Bluetooth. According to Johnny McClintock, manager of aptX sales and marketing at Qualcomm, SBC was meant to keep the bitrate of the music as low as possible, which benefits the connection but the music quality is not. “The result is a bit rate of barely 200kbps,” says McClintock. “As a result, almost all tones above 16 kHz are lost when audio is sent via SBC”.
Bluetooth has been catching up in recent years in the field of audio.
When it became possible to send more data via Bluetooth, Qualcomm bought the codec aptX to the world of Bluetooth. The aptX concept dates back to the 1980s, where it was used to transmit audio over the Internet with as little loss of quality as possible. The codec as we use it today in Bluetooth was introduced in 2008. In contrast to the barely 200 kilobytes per second used at 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 it also sounds largely as CD quality.
Fine, better, best aptX
Two varieties 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. For comparison: at SBC there is usually a delay of about 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/48 kHz. There is still compression, but with aptX HD it is reduced to the minimum. With aptX and all variants, the rule applies: both devices must support it.
An improvement in sound quality can never hurt, but there is no guarantee that you will always hear the difference. As we already said, aptX makes it possible to make music sound like CD quality but to play that, you also have to play the music of CD quality or higher.
With a simple MP3 file on Spotify, you will notice little difference. Such music files are already quite compressed so that many details in music – especially in the higher and lower frequencies – quickly disappear. Music of CD quality or higher still contains many of these details and is, therefore, more effective with aptX.
Do you have a smartphone with aptX, high-quality music and headphones or speakers with aptX? Then it is blown away by the music lover. Finally, you can enjoy music in CD quality wirelessly.
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