[Hitchhiker]

The nuance is if one thinks deeply .. auditory interference is part of the human experience .. we even do not mind it since artifical and natural sources are always meshing in and out. This is why the Walkman took off since people were already listening to music from the time of live performances onward to the Edison era and then portables.

Glass if one thinks about it deeply is something unnatural.. microscopes, telescopes, vision impairment correction or shade from harmful sun.. or immersive , time disruptive experiences like a movie.

So the key barrier that glass concept is going to face is user rejection beyond the initial bubble crowd. Average people already have a certain context in which they find artificial inputs acceptable ( TV etc ).

Our distinction between natural and artificial sources of audio is different to visual.

I may be entirely wrong and Google may change the habits of a lot of young kids .. that is actually a rather strange and terrifying thought.