Proto Man has a particularly deep voice, so I figured there would be no way for him to pass as Roll if he didn't at least attempt to disguise it. However, because I don't have any standard way of differentiating one characters speech from another, I had to come up with a different plan. SO I made the text a little smaller to imply that he's speaking more softly, and I also placed it a little higher in the text balloon to imply that he's also speaking higher than normal. And despite Roll's objections, it appears to be working well enough to fool Dr. Light. Of course, he's still in a bit of grief-stricken daze, but you can't argue with results. Roll on the other hand doesn't actually disguise her voice. So far she's only had to talk to the reporter who probably doesn't know Mega Man well enough to recognize it's not his voice, and definitely doesn't know Roll well enough to recognizer her voice.
However, while we're on the subject, I figure that it's pretty much common knowledge that Rock and Roll are robots built by Dr. Light. And while I figure it's also common knowledge that Mega Man is Dr. Light's creation, I do assume that most people don't know, or more likeley just don't care enough to notice that Mega Man and Rock are the same robot. I mean, when your secret identity is another robot, built by the same creator, who cares if it's secret or not?
can't they change their voice modulators? like the time when megaman made a snide comment about Dr. Light sounding like Elmer Fudd and got changed to sound like a little girl?
Yes, but they don't have the equipment or programming to tune their voice to the precise tone, frequency, level and whatnot necessary to get the exact voice. Basically, this is just Proto Man's best guestimate. Dr. Light on the other hand, probably just upped the pitch on Mega Man's voice for Mega Man 8.