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
Perception of infrasound the right source loudspeakers when they were positioned at different angles from the elephant’s head. The elephant could localize sounds best at a frequency below 1 kHz, with perfect identification of the left or right speaker at angles of 20 degrees or more, and chance level discriminations below 2 degrees. Sound localization ability was measured to be best at 125 Hz and 250 Hz, intermediate at 500 Hz, 1 kHz, and 2 kHz, and very poor at frequencies at 4 kHz and above. A possible reason for this is that elephants are very good at using interaural phase differences which