I do have a doubt when re-reading myself.
HR is using weaker encoding, so it’s more difficult for the decoder to properly retrieve the speech frames. However the BER is the number of bits that were not properly received on the radio layer. It does not depend on the encoding.
So what i say before sounds true, still.
But there is perhaps a second effect of the HR that will degrade the RXUAL & BER measurements. I’ll investigate this and will do some tests myself. If you’re seeing it , then it must be true ! 🙂