Wait… Am I missing something here? I don’t understand why a 10kHz wave would do anything to a pair of speakers at a distance.
Unless the speakers are actively playing the output of a radio themselves, it’s not like 10kHz waves will randomly affect the membrane of an electrostatic speaker. The membrane vibrates by an electric signal, not by EM radiation.
Even then, I feel like radios don’t just output whatever their antenna picks up raw. The electronics in radios tune to specific frequency bands and decode the underlying signal by means of FM or AM, and it is that underlying signal that gets played by the speakers.
So even a stronger encoded signal doesn’t necessarily mean louder speaker volume. It would just mean a clearer, less-noisy song.