It's shit tier audio quality, plain and simple. Voice actors did a fantastic job and either the studio or whoever compressed the audio when it was going in to the game completely fucked it up.

It's in the Japanese dub as well but they don't have nearly as many S sounds and just the way they talk means it's nowhere near as grating.

I absolutely fucking hate that shit and it damn near ruined the game for me, right now I'm just trying to make the best of it with the Japanese dub but if that wasn't there i would have dropped the game completely. It's funny that you mention the teacher because when she was talking i almost threw my controller at the TV, I've never felt that but that kind of hissing annoys me so fucking much and she does it about ten times in one line.

I actually broke my usual budget for this game and i got it digitally too as it was hard to find physically so i was looking pretty hard to justify buying it, so much that even a single line would do. Instead the game has the one thing i can not stand under any circumstances, they may as well have recorded nails on a chalkboard for every line as far as I'm concerned.

I don't care how good the rest is supposed to be there's no way I'm going to spend a hundred hours listening to constant hissing. Needless to say i won't be buying anything by Atlus again, they can fuck right off.