It seems to be happening on the speech sections only. It is definitely not on the original recording, but seems to be on the master cd. and of course is being duplicated on every copy.

It sounds like a buzzer for a door bell, but is getting worse and happening quite often. I suspect it is the burner and we are changing it tonight to see the results

Any further advice welcome as we try to get the best recordings for our listeners who are blind

Derek M