Any vibration is just a signal. We don&#x27;t actually have a direct experience with a sound, hearing is our brains interpreting the nerve signals generated by tiny organelles jiggling in our ears. What is concrete then, is only the shape of the signal, but not the medium through which it propagates.<p>This device just acts like a gigantic hearing device. Except it&#x27;s not pressure waves, but the fabric of the universe which reverbates.<p>Note that the frequency of the signal is indeed in the audible range.<p>Anyway, I was a bit irritated of this same phrase, but because I tought radio astronomers had been listening to skies for quite some time now.