the frequency of the lowest sound that the normal human ear can perceive is 20.
the frequency of the lowest sound that the normal human ear can perceive is 20.
frequency of the lowest sound that the normal human ear can perceive?
20
sounds used by animals that fall within the scope of bioacoustics include a wide range of frequencies and media, and are often not ""sound"" in the narrow sense of the word (i.e. compression waves that propagate through air and are detectable by the human ear). katydid crickets, for example, communicate by sounds with frequencies higher than 100 khz, far into the ultrasound range. lower, but still in ultrasound, are sounds used by bats for echolocation. on the other side of the frequency spectrum are low frequency-vibrations, often not detected by hearing organs, but with other, less specialized sense organs. the examples include ground vibrations produced by elephants whose principal frequency component is around 15 hz, and low- to medium-frequency substrate-borne vibrations used by most insect orders. many animal sounds, however, do fall within the frequency range detectable by a human ear, between 20 and 20,000 hz. mechanisms for sound production and detection are just as diverse as the signals themselves.
bioacoustics
being approximately the lowest sound intensity hearable by an undamaged human ear under room conditions.









































the proper notations for sound intensity level using this reference are or , but the notations , , dbsil, or db are very common, even if they are not accepted by the si.









































the reference sound intensity "i" is defined such that a progressive plane wave has the same value of sound intensity level (sil) and sound pressure level (spl), since









































the equality of sil and spl requires that









































where is the reference sound pressure.









































for a "progressive" spherical wave,
sound intensity