UnitS - Waves& Sound Salma. who is always in a great mood in the morning, arrives in class singing. [f the frequency of the sound waves she is producing is 969 Hz, and the speed of sound in our classroom is 355 mjs, determine: a) The temperature in our classroom. b) The wavelength of the sound waves. c) The length ofa closed tube that would produce the second resonant length. Draw the standing wave in the lube