I don't think you looked all that hard, as this is central in the book "Introducing Bluetooth LE Audio" available for free here https://www.bluetooth.com/bluetooth-resources/le-audio-book/...

LE Audio is built around a channel concept, where a channel is unidirectional and a connection can have multiple, e.g. listening on 2 stereo channels and when a call arrives enabling 2 mic channels in the other direction for stereo microphones

Don't go around throwing shade at the spec authority if you haven't read the spec