A Zwicker tone is a short-term
auditory illusion which resembles
tinnitus
Tinnitus is the perception of sound when no corresponding external sound is present. Nearly everyone experiences a faint "normal tinnitus" in a completely quiet room; but it is of concern only if it is bothersome, interferes with normal hearin ...
(ringing of the ears). It was discovered in 1964 by
Eberhard Zwicker at
Bell Labs
Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984),
then AT&T Bell Laboratories (1984–1996)
and Bell Labs Innovations (1996–2007),
is an American industrial Research and development, research and scientific developm ...
. The Zwicker tone can be described as follows: while listening to broadband noise ("
white noise
In signal processing, white noise is a random signal having equal intensity at different frequencies, giving it a constant power spectral density. The term is used, with this or similar meanings, in many scientific and technical disciplines ...
") with a
spectral gap
In mathematics, the spectral gap is the difference between the moduli of the two largest eigenvalues of a matrix or operator; alternately, it is sometimes taken as the smallest non-zero eigenvalue. Various theorems relate this difference to othe ...
, if it is switched off a faint tone lasting for several seconds can be heard. In the silence, most listeners hear a tone corresponding to the spectral gap. The pitch strength corresponds to the pitch strength of a
pure tone
Pure may refer to:
Computing
* A pure function
* A pure virtual function
* PureSystems, a family of computer systems introduced by IBM in 2012
* Pure Software, a company founded in 1991 by Reed Hastings to support the Purify tool
* Pure-FTPd, ...
of same pitch and sensation level.
References
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Psychoacoustics