117 This professor bounces sound waves carrying music that can not be heard out loud but can be heard in. (m.youtube.com) posted 1 year ago by GGRockz 1 year ago by GGRockz +117 / -0 43 comments share 43 comments share save hide report block hide replies
Wavelength (λ) = 0.005277 m. Is that 5.2mm?
https://onlinecalculator.guru/physics/wavelength-for-medium-sound-in-air-at-20-degree-celsius-at-frequency-65-khz/
4200 meters per wave length.
Amateur radio 20 M is in the 14Mhz range.
Some of us tend to automatically compute frequency into free space RF wavelengths. Sound in various mediums is totally different.