Q. If a woman singing and modulating her voice to sound like a man's? Is there a kol ishah prohibition issue in either case? That is, do we go after who's singing, or what it sounds like on the recording?
A. Our Rabbonim sugested that it depends on the way the connection is between the original voice of the woman and the resulting voice actually being heard. See new more detailed Shaila soon.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller, Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit’a