I'll tell yer summat that doesn't exist: the bottom note on a fiddle. It's about 192hz, and the box on a fiddle isn't big enough to accomodate the wavelength and doesn't vibrate at that frequency, only those of its harmonics. That frequency represents less than a thousandth of the energy in the vibrating air produced, and is consequently below the threshold of human hearing. The listener's brain invents the implied note from the gaps between the harmonics.