Gotta say, that was one crappy manga >:^(
Now now Master, that's kinda rude to the mangaka, she may have tried very hard. Don't be a meanie
http://www.mangago.me/read-manga/koe_shika_mienai/
I am pretty sure this is it~!
Eh I just remembered the manga while I was reading another. I haven't read it in a while so I forgot what happens. When it comes to rereading manga I normally just skim through it rather than just reading it properly so I remember what's happening. Doesn't necessarily mean I want to read it because it's good it's because I just remembered it and want a recap.
The uke is inaudible due to a past relationship that had prevented him from making any sounds during sex (I think) because his voice was said to be disgusting.
The seme & uke are office workers.