It's explained in the section on SCO at the link in my original comment: > Bluetooth supports data rates of up to 3 MB/s and fully uncompressed stereo audio on

It's explained in the section on SCO at the link in my original comment: > Bluetooth supports data rates of up to 3 MB/s and fully uncompressed stereo audio only needs about 1.4 MB/s. But, the 3 MB/s data rate is for an Asynchronous Connection Less (ACL) transfers under ideal circumstances. In practice, even 990 kb/s (what Sony’s LDAC codec uses) is not trivial to transmit reliably. But the Hands Free Profile doesn’t even use ACL, but Synchronous Connection Oriented (SCO) transfers. These have a fixed data rate of 64 kbit/s (bidirectional). More here: https://habr.com/en/post/456182/ https://habr.com/en/post/456182/ > Synchronous Connection Oriented (SCO) and its enhanced version Enhanced Synchronous Connection Oriented (eSCO) are the modes used for Bluetooth voice transmission. The mode allows you to transmit sound and voice strictly in order, with a symmetrical speed of sending and receiving, without waiting for confirmation of transmission and re-sending packets. This reduces the overall delay in the transmission of audio over the radio channel, but imposes serious restrictions on the amount of data transmitted per unit of time and adversely affects the quality of the audio. When this mode is used, both the voice from the microphone and the audio are transmitted to the headphones with the same quality. You should also know that (as mh- points out), BTLE is an separate protocol that is not used for audio. Audio devices use Bluetooth classic. That's also explained at https://habr.com/en/post/456182/ https://habr.com/en/post/456182/ in the "Bluetooth 5, Classic and Low Energy" section.