This topic interests me greatly, as I recently started to play the fiddle ( I love it and can spend hours playing) and also have some preexisting hearing loss from indiscriminant use of power tools in my younger, more foolish, years. I don't wish to aggravate the condition. I wear hearing aids and prefer to play without them, or with the volume turned down. I would like to know if I should consider ear protection. I did recently discover the practice mute ( or "silencer" as I like to call it, as in the wrong hands some fiddles can be lethal instruments). I purchased one in preparation for an incoming house mate, who may not fully appreciate my early morning serenades. It cuts the sound by over half. I can play watching T.V., adding my own soundtrack, and still hear the dialogue. I was cautioned by an expert fiddler that using the mute continuously can be harmful to the instrument, and you should spend at least equal time playing at normal volume to reverse the effects of damping the vibrations. I don't know the science at work here but it sounded reasonable to me. Also there are smaller devices to decrease the sounds slightly that fit behind the bridge, useful for playing in a group with less vociferous instruments. I don't know if these would be useful to minimize potential hearing loss. Hope to hear more on the subject.