The calculation by tech99 is of course correct for linear waves, which is what we normally think about. These kinds of calculations also apply to electromagnetic waves and dish antennas.
However, I have been to museums that use the 'audio spotlight', so a person standing in front of an exhibit hears the audio track, and a person a few feet away doesn't hear it at all. It really confused me the first time I experienced it, and I couldn't figure out how it worked. I later learned that this technology is based on nonlinear acoustics. I believe it transmits an ultrasonic signal that has been amplitude-modulated by the audio track, and through nonlinearities in the air a fraction of the energy is converted to audio frequencies. Here is an abstract that gives the basic idea
https://asa.scitation.org/doi/pdf/10.1121/1.389414
jason