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
Radio-controlled aircraft the 1983 FCC reform that introduced "narrowband" RC frequencies - at 40 kHz separation from 1983-1991, and finally at 20 kHz separation from 1991 onwards, to the present day with fifty frequencies on 72 MHz solely for flying models. The 75 MHz band became usable only for ground-based RC modeling (cars, boats, etc.) in the same timeframe, with the transition also occurring through to 1991, having 30 frequencies available at the same 20 kHz channel separation. Canadian modelers today flying on VHF-band RC gear use the same 72 and 75 MHz frequencies as American hobbyists do, for the same types