411 REFERENCE · Wiktionary
Ormsby filter
Reference material by Wiktionary contributors. This retains its source identity and is not 411 news reporting.
English
Noun
A filter of trapezoidal shape specified by four corner frequencies, f1 through f4. The filter rejects below f1 and above f4, is linear from f1 to f2 and from f3 to f4, and is flat from f2 to f3.
See also
Butterworth filter