A dog whistle has a frequency of 23,5 KHz, and a second dog whistle has an unknown frequency. Neither of the whistles can be heard by humans (hearing range: ~16000 Hz) but when both whistles are blown simultaneously, a tone of 10 KHz can be heard. What is the frequency of the second dog whistle?

Question

anonymous · Answer

This is   a beating frequency  problem: the one you can hear is the first whistle frequency minus the second one frequency...the frequency we are looking for is 33,5kHz ( you would hear the other possible answer that could be 13,5kHz.)