Correct Response: C. The speed of sound increases as air temperature increases. Therefore, if the temperature of the air in the pipe increases, the speed of sound in the pipe will also increase. The wavelength of the fundamental frequency (A) for a pipe that is closed at one end is equal to four times the length of the pipe, so the wavelength will change only if the length of the pipe changes. Although the fundamental frequency and the harmonics will all shift upward, they will do so by the same factor as the velocity. The ratio of the harmonics produced in the pipe (B) will therefore remain the same, since harmonics by definition are whole number multiples of their fundamental frequency. The number of overtones produced in the pipe (D) will not change, although their frequencies will shift upward by a common factor.
