Sinusoidal tones have frequencies of 439 Hz and 443 Hz. One might still hear beats, but the effect would be reduced.
All waves can propagate around obstacles to some extent as a result of diffraction.
The distance is comparable with the wavelength, or at most a few wavelengths. This is why we can hear sound from an invisible source sound propagates around a corner while light, with its very short wavelength, does not. Flutes produce generally higher frequencies, and thus shorter wavelengths , than French horns. Thus, the sounds from a French horn should propagate around a corner more effectively than those from a flute. With this wavelength one could see body parts as small as a small grape, i.e. large stones, tumors, organs, parts of a fetus, etc.