I don't know, requiring several phones within hearing range seems like it would severely limit the applicability of this technique.
If you think N phones provides at best N*(maximum sample rate of one phone) and that's assuming their phases a perfectly misaligned I'd think you'd still need quite a few to get something.
Plus the 100 Hz figure is optimistic. I dunno what kind of anti-aliasing these things have. If none you get an aliased signal and with a low order filter the practical maximum frequency detectable would be even less.
Plus the 100 Hz figure is optimistic. I dunno what kind of anti-aliasing these things have. If none you get an aliased signal and with a low order filter the practical maximum frequency detectable would be even less.