> Your comment brought my mind to voice actors. They easily change their voices. Deep fakes also come to mind.

Voice actors, deep fakes, replay attacks (recordings from a TV/computer/phone) - mitigated. As in my earlier comment where teen voices have a signature, these all have unique signatures as well. The ongoing part is staying up-to-date with the latest synthetic (deep fakes/AI generated) as those are getting better each day.