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
Longwave ground-wave propagation suffers less attenuation due to limited ground conductivity at lower frequencies. Long-wave carrier frequencies are exact multiples of 9 kHz; ranging from 153 to 279 kHz, except for a French-language station, Europe #1 in Germany. This station kept correctly spaced channels spacing for 4 months—only 7 years ago, and all Mongolian transmitters are 2 kHz above the internationally recognized channels. Until the 1970s, some long-wave stations in northern and eastern Europe and the Soviet Union operated on frequencies as high as 433 kHz. Some radio broadcasters, for instance Droitwich transmitting station in the UK, derive their carrier frequencies