I personally don't buy the whole decibel theory. Even if you look at NOISH and OSHA they have different threshold levels.
Certain noises, usually low-frequency artificial ones, cause me great distress even at very low decibels.
Something intuitively just tells me they cause harm in some way whether it's to hearing or not. Yes I know what the "science" says and I know what OSHA and NIOSH (whom I wouldn't be surprised if they have lobbyists from industry who are reliant on workers being exposed to noise to make money).
I think damage is caused by not just the decibels but also other parameters of the noise whether that would be frequency other even other markers that have yet to be established or are too complex to establish.
I couldn't image you put a mouse next to 40 db low frequency artificial noise all day and they are not going to suffer any problems from it.