jbtsax said:

There was a lengthy thread on this topic a while back. The expansion of the metal of the instrument is so small that its effect on the pitch is negligible. The speed of sound is determined by the temperature and humidity of the air. In dry air at 72 degrees F the speed of sound is approximately 345 m/s. At 75 degrees F the speed of sound is approximately 346 m/s.

Pitch (frequency) is related to the speed of sound by this formula:

**Frequency = velocity (speed of sound) / wavelength**

Using this formula for an A =440 the wavelength is .784 meters. When the temperature rises from 72 to 75 degrees F, the speed of sound increases 1 m/s and therefore the pitch of A rises to 441 vps or about 4 cents on the tuner.

John

A very good explanation John.

Like I said, I am no expert.

However, I would have thought that as the temperature increases,

the air density decreases due to expansion.

Therefore the speed of sound would decrease in this situation,

as I seem to recall that the speed of sound is greater through

more dense material.

Again however, I do note that when we have warmer temperatures

here, the air pressure given by the weather forecasters is higher.

Can someone enlighten me :? :?