Most certainly but the most fascinating fact is that the human ear is a wonderful mixer and it automatically selects, emphasizes, etc. the lowest frequency product.
Fascinating in my book.
When I learned this I said “bullshit”....I actually took two oscillators and speakers at the frequencies mentioned and I padded them into a summing pad. The dial tone appeared and I was a believer.
It’s mathematics!..............
Understood but it is a wonderful byproduct that he human ear suppresses the two higher tones and selects the lowest product, n’est pas?
You might not be aware, but aircraft landing systems that locate the aircraft on the center of the runway use that same system to modulate an RF signal that is received by the aircraft from transmitters on either side of the runway.
It’s been a long time, but IIRC, the tones are 120 and 90 Hz. Too far to one side and you get solid freq of one or the other. Right down the middle you get the mixture of the two at equal amplitudes...........
https://en.wikipedia.org/wiki/Instrument_landing_system