Hypersonic effect Hypersonic effect The hypersonic effect is a term coined to describe a phenomenon reported in a controversial scientific study by Tsutomu Oohashi et al., which claims that, although humans cannot consciously hear ultrasound (sounds at frequencies above approximately 20 kHz), the presence or absence of those frequencies has a measurable effect on their physiological and psychological reactions. Numerous other studies have contradicted the portion of the results relating to the subjective reaction to high-frequency audio, finding that people who have "good ears" listening to Super Audio CDs and high resolution DVD-Audio recordings on high fidelity systems capable of reproducing sounds
Acoustic metamaterial from below frequencies used for modern radio to gamma radiation at the short-wavelength end, covering wavelengths from thousands of kilometers down to a fraction of the size of an atom. That would be wavelengths from 10 to 10 kilometers. The long wavelength limit is the size of the universe itself, while it is thought that the short wavelength limit is in the vicinity of the Planck length, although in principle the spectrum is infinite and continuous. Infrasonic frequencies range from 20 Hz down to 0.001 Hz. Audible frequencies are 20 Hz to 20 kHz. Ultrasonic range is above 20 kHz.