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
500 kHz kHz to amateur radio use. In Belgium, amateurs are allocated a 501 to 504 kHz on a secondary basis on January 15, 2008. Only CW may be used with a maximum ERP of 5 W. In Norway, the band 493–510 kHz was allocated to radio amateurs on November 6, 2009. Only radiotelegraphy is permitted. In New Zealand, the band of 505 to 515 kHz was allocated temporarily, pending an international frequency allocation. In the Netherlands Amateur radio operators have allocated the band from 501–505 kHz with a maximum of 100 watts PEP on January 1, 2012. 500 kHz The radio