The pitch is sharp when the instrument is "cold" because the instrument shrinks as it gets colder.
The pitch of a note in a wind instrument is determined by the length of the instrument. The figure below shows how sound waves bounce around in a pipe (or instrument)
The shorter the instrument is, the faster the sound waves will bounce, and so the frequency (pitch) goes up. A piccolo is shorter than a flute, so it plays higher notes.
When the instrument is cold, the instrument is shorter, and the pitch goes up. When it gets warmer, the instrument expands, and the pitch goes down.
We would like to find out how much the pitch of an instrument changes as a player warms up, and we would like your help. If you play an instrument, and are willing, we ask you to do an experiment and send us the data.
1. Find an instrument that can tell you what frequency (in hertz) you are playing (eg. computer, oscilloscope) and play your tuning note (without warming up).
2. As you practice, every minute, check your pitch again. Repeat this for several minutes.
3. Record the pitches and the room temperature, and send the data to us with this form
Thanks!