It's definitely Bishoff. Guarantee it. The voice distortion can only hide your voice to such an extent. It doesn't hide your speech habits, general accent, and how fast you usually talk. I'd say the match is nearly 70%. . .but since no one else on the roster talks like him, I'd say 90-95% chance it's Bishoff. The other 5-10% being only that someone was trying to sound like Bishoff to throw people off.
Or they used Bischoff's voice to throw us off. They have been switching who the guys in the masks are to throw us off.