A certain dog whistle operates at 23.5 kHz, while another (brand X) operates at an unknown frequency. If neither whistle can be heard by humans when played separately, but a shrill whine of frequency 9200 Hz occurs when they are played simultaneously, estimate the operating frequency of brand X.
____Hz
2 answers
The mystery whistle has a frequency that is 9200 Hz or 9.2 kHz from the other, which means is at 23.5 ±9.2 kHz, which means the two options are 32.7 kHz (above human hearing - Ultrasound) or 14.3 kHz (below human and dog hearing - Infrasound) Then the other whistle must be the higher frequency of 32.7 kHz.
It would have to be 32.7 kHz because humans can hear 14.3 kHz