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
History of the Tesla coil New York for researching them, initially repeating Hertz's experiments. He first developed alternators as sources of high frequency current, but by 1890 found they were limited to frequencies of about 20 kHz. In search of higher frequencies he turned to spark-excited resonant circuits. Tesla's innovation was in applying resonance to transformers. Transformers functioned differently at high frequencies than at the low frequencies used in power systems; the iron core in low frequency transformers caused energy losses due to eddy currents and hysteresis. Tesla Tesla invented the Tesla coil during efforts to develop a "wireless" lighting system, with gas discharge light