Semi Perminant Singing magic.
Semi permanent singing magic is Angel magic used by Denise on Jane in the episode Announcement of Prevention.
The magic does give someone who lost his voice back to that person only with one downside. The person who the magic is used on only has a singing voice and cannot use regulair non singing speech.
Jane explained to Denise that she needed her voice back because she was doing a memorial speech for the recently deceased drama department mascot Hamlet the Hamster. Denise then used voice magic on Jane. When she asked Jane to test if the magic worked Jane tested and notified Denise in a quite amusing way that something went wrong. (Testing Testing this is most erasting i can only sing i dont have a speaking voice ohh off all the things you could have done this is the worst choice)
Later Denise and Porter went to visit Dr. Cassibi to ask help for the problem that Jane could only sing and couldnt use her regulair speaking voice. After asking Denise several question about magic that she could have used Dr.Cassibi mentioned semi-perminant singing magic and after Denise acted (rather unconvincing)like she would never use Semi Perminant singin magic Dr.Cassabi told Denise that Semi-Perminant singing magic cant be undone you have to wait till the magic wears off which is about one week.