That's a more natural way to consider the resonance, certainly. What I was getting at is that if we were using a 7hz tone to explore a big room, we couldn't tell if there was a chicken in there or not. We'd have a hard time sensing an elephant. Let alone exert enough of a force to harm. Because the wave is so much larger that they barely interact.
Without disputing the conclusion, is the wavelength the right measurement, or should that be half the wavelength?