Not all Bluetooth is equal
Bluetooth audio is convenient, fussfuss-free, and easy. But not all Bluetooth devices are equal. Here’s Bluetooth audio dio in a nutshell.
Early Bluetooth wireless audio devices sounded significantly worse than their wired counterparts, and the reason why is because music data has to be compressed before it can be transmitted wirelessly. This is necessary because transmitting lots of data can put a serious drain on batteries; less data means less power drain. So, the way music data is transmitted and therefore how it sounds, is dependent on the codec used for transmission.
SBC stands for 'Low Complexity Subband Coding' and, it is the default codec for all Bluetooth audio devices. It wasn’t designed for music listening or audio fidelity. Instead, it was designed so that audio can be transmitted using the least power possible. As a result, listeners with keen ears will hear a distinct drop in audio quality. Worse still for discerning users is that there are many levels of SBC, and users cannot easily tell which particular level of SBC is actually being used by the devices for streaming. At best, SBC streams audio data at a bitrate of around 328kbps – comparable to the highest quality MP3 files.
Moving up from SBC, we have aptX, which is a codec developed by a company called CSR and acquired by Qualcomm in 2015. Unlike SBC, aptX’s roots are founded in audio fidelity; created using data gleaned from psychoacoustic research. It aims to deliver near CD-quality audio. And indeed, some audiophiles have reported better streaming performance.
And even though aptX is one of the more popular Bluetooth audio codecs, it is not supported by all devices. To get aptX-quality Bluetooth audio, both the transmitting and receiving devices must support aptX. iOS users should take note at this point because iOS devices do not support aptX.
So how then can an owner of an iOS device get better quality Bluetooth audio? The answer is AAC, another codec designed specifically for audio use. Like aptX, it requires both transmitting and receiving devices to support AAC to work. Audiophiles have found AAC to sound comparable to aptX, but the bigger issue is popularity of the standard. There are fewer third-party devices today that support AAC than aptX. This means that owners of iOS devices must look a bit harder to find an AAC-compatible Bluetooth device if they want the best Bluetooth audio experience.