sound with frequencies below the audible range.
Origin of infrasound
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
soundlike waves having a frequency below the audible range, that is, below about 16Hz
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Sound whose wave frequency is too low (under 15-20 hertz) to be heard by humans. Some animals, such as elephants and whales, emit calls at infrasound frequencies. See Note at ultrasound.
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