Thankyou psybbo. Had theatre vouchers as a present some years back, but by the time Mr.c and I decided what we both wanted to see 'Whistle down the wind' had finished in London and we ended up seeing Mama mia which neither of us cares if we ever see again!
Air blowing over the edge of a tube will produce a standing wave in that tube. Besides the fundamental frequency, other harmonics are also produced. This may sound like the notes produced by a bugle and can sound very creepy indeed,