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
Comparison of analog and digital recording up to 20 kHz. The sampling theorem also requires that frequency content above the Nyquist frequency be removed from the signal to be sampled. This is accomplished using anti-aliasing filters which require a transition band to sufficiently reduce aliasing. The bandwidth provided by the 44,100 Hz sampling frequency used by the standard for audio CDs is sufficiently wide to cover the entire human hearing range, which roughly extends from 20 Hz to 20 kHz. Professional digital recorders may record higher frequencies, while some consumer and telecommunications systems record a more restricted frequency range. High quality reel-to-reel machines can extend from