Hobby Horse warning. I hear a lot of people calling the person that twiddles the knobs, a Sound Engineer or Sound Man. To me both are wrong, I am an Engineer, I studied Mechnical and Electronic Engineering for 7 years before I was allowed to use the letters IEng after my name. So he/she is not an engineer. As a rule of thumb an Engineer designs it and a Technician fixes it when it goes wrong.
Sound man is sexist.
To diffrentiate the person from the machine that records, the BBC calls t