I used to borrow fake books from the local library all the time when I lived in Maine. I tried playing them on the clarinet. I don't think it ever occurred to me that they were just the vocal parts. I was just interested in the transcription.

My voice instructor wanted me to email her for a copy of her vocal health guide, so I tacked on a question about voice parts. I imagine that this is something we would have discussed after she thought I had a reasonable level of technique (she is having me move my face in ways that feel fairly decidedly unnatural, which is having the effect of opening up areas of my body and allowing what tones that do come out to be a little more even from one part of my range to the other).