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
160-meter band 160-meter band Just above the mediumwave broadcast band, 160 meters refers to the band of radio frequencies between 1800 and 2000 kHz. For many decades the lowest radio frequency band allocated for use by amateur radio, before the adoption, at the beginning of the 21st century in most countries, of the 630 and 2200 meter bands. Older amateur operators often refer to 160 meters as the Top Band It is also sometimes referred to as the "Gentleman's Band" in contrast to the often-freewheeling activity in the 80 and 20 meter bands. The 160 meter band is the oldest amateur band