I think that the problem is much more complicated, and involves the phenomenology of sound, which is hard to capture. Rock music is music where the listener wants to be physically pressed by the music and saturated by the sound (this is true of techno-pop etc.). The louder the sound the more environmentally powerful it is: meaning is based on variation in a given underpinned environment ("the ground is sound"). This style, associated with amplification, has taken over audience expectation. It is not for listening, it is for being in. If a young audience has to bend forward to listen, it is not just too quiet, it is outside them: it does not support them. Classical audiences sought volume too, but it was in a context of actively searching for nuance in sound, and meaning in sound: volume is part of crescendo and decrescendo, and so on. Its fundamental ground is silence, not sound. The problem is not that people are getting deaf to sound: they are getting deaf to silence, which affects the meaning of the sounds that give their musical experience meaning.
Or some groping thought like that....

yours, Peter T.