TV documentaries on marine life often feature the evocative sounds of whales communicating with each other (apparently), over very long distances.
The frequency of baleen whale sounds ranges from 10 Hz to 31 kHz, whereas experiments have shown that a healthy young person hears sound frequencies from approximately 30 to 20,000 hertz.
So the film makers use the speeded up sound recordings provided to them by the whale research people to let us all hear whale song.
I would also like to ask this on a more general level than just whale sounds, as I think it's a related question.
I don't know anything about acoustics but I have a feeling there must be a tradeoff in the original information carried by a signal, acoustic or electromagnetic, when we alter it's frequency and I wonder is there a formal measure of this change in information content?