Temperature and Instrument Pitch
Name: Christina K.
I am just wondering why temperature effects how a musical instrument sound. My band
teacher told me that depending on the temperature, the sound can go sharp or flat.
The effects of temperature on a musical instrument depends upon the instrument. Variations in
temperature affect humidity which is a complicating factor. It also affects the density of air. Both
would affect brass instruments. Higher temperature will decrease the tension in strings. The dimension
of the pipes in an organ will be influenced by temperature. These are all the effects of the "physics",
musicians with their tuned ears compensate for temperature changes except for instruments like a piano
whose tuning is "fixed".
As air warms up the sound wave will travel faster. The speed of sound in air depends upon the
temperature. The warmer the temp., the faster the sound moves.
As far as the pitch goes, I think it must depend on the instrument. My guitar goes flat as it gets
warm because the strings expand slightly and become longer. In a wind instrument, as the wave
travels faster in the instrument, the frequency will increase making the instrument go sharp. The
speed of sound is equal to frequency times wavelength, v = f L. The wavelength is determined by
the physical size of the instrument and is fixed. So, if velocity increases, and L is fixed,
frequency must increase to balance the equation. The higher the frequency, the higher the pitch. So,
I guess strings go flat, woodwinds, and brasses get sharp, and percussion depends on the type of
instrument, how the sound is physically produced, and what material the sound must travel through.
I hope this answers your question. What do you play? Have you noticed this before? Any other band
members of yours that can verify this?
Good question, good music and science, we will call it ACOUSTICS.
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Update: June 2012