There were several questions on last night's "University Challenge" (a slightly up-market quiz program on BBC2") in which the team were played tapes of 2 people singing and had to guess the "vocal ranges".

At first I thought "How strange, how would they know if it was one and a half or two octaves, etc?" but when the first answer came it was "Tenor and Soprano". The remaining answers were things like Mezzo-soprano, Baritone, etc.

So can anyone tell me how these are defined, and also what is the average range of an untrained human voice (Mine is about one and a half octaves at best though some of the notes at the low and high end are somewhat strained, well probably they are all a bit of a strain to hear/ear!)?

I presume that the ranges are defined with respect to a fixed pitch nore (perhaps Middle C on a Piano?).