ATC recordings are recorded "off air" so the signal has been transmitted....... they are a good record of what the controller transmitted but only that, you need the aircraft voice recorder to be sure of what reached the aircraft and its relationship to other distractions
Right, thanks for that info, it's a very sensible way to ensure the record of what was transmitted is accurate and valid.
I appreciate it's probably not a factor in this case*, but it seems to me that if that was the evidence referred to in the report to imply the transmissions were received clearly then, as you say, without the aircraft voice recorder it's stretching it a bit!
*That said, something caused four people in two crews to make similar errors about what they heard...so there has to be a common factor relating to comms surely?