I just remembered a documentary I saw on tv about 20 years ago. It was called What is Music?

It showed that an instrument like a trumpet changes it's sound the longer and louder a note is blown, i.e. the sound becomes not just louder, but fuller and richer. It was represented visually on the electronic graph-thingy, (sorry, just read John in Kansas's posting: oscillographs/oscilloscopes) like the music visualisations on Windows Media Player, and started small then gradually enlarged, like the transition in the shape of a pear, from top down. Maybe what shows on the graph-thingy is what was recognised by voice teachers a long time ago.

I'm not explaining this very clearly. If you listen to the trumpet sound on a good electronic piano, like my Yamaha, the longer you press the note, the richer and fuller the sound gets.

(I recorded the tv show on a video tape, which I still have, but don't now have a video player to play it on, and the tape is probably kaput by now, too. Unfortunately, "What is Music" is one of the phrases which tends to stump Google, because it returns about half a million hits, and it's not easy to narrow it down to the documentary, especially since I cannot remember specifics about who was in it, or where it was made. I'd love to be able to buy the DVD.)

Helen