I am researching metal detectors to use while diving - I like Whites new Surfmaster Dual Field but I am concerned with the "Threshold" tone while wearing my wet suit hood and the bubble noise. I understand that one would like the threshold as low as possible and listen for the tone to "Drop out". Can this be a problem or is there a solution. Oh, this will be my fist MD! If I got some info messed up, please help me out. NEWB...