Answer
The increased temperature would cause 2 things -
First thermal expansion of the pipe hence increase in speed of sound in the pipe. The pipe would get longer which increases the wavelength of fundamental and other harmonics. A greater wavelength would result in lower frequencies.
Secondly, on the other hand, increased speed of sound would result in higher frequencies of sound.
Thermal expansion is quite small, so the dominant effect would be due to increased speed of sound. The net outcome would be to produce higher frequencies.
Work Step by Step
The increased temperature would cause 2 things -
First thermal expansion of the pipe hence increase in speed of sound in the pipe. The pipe would get longer which increases the wavelength of fundamental and other harmonics. A greater wavelength would result in lower frequencies.
Secondly, on the other hand, increased speed of sound would result in higher frequencies of sound.
Thermal expansion is quite small, so the dominant effect would be due to increased speed of sound. The net outcome would be to produce higher frequencies.
