two-tone diaphone

two-tone diaphone

[′tü ¦tōn ′dī·ə‚fōn]
(engineering acoustics)
A diaphone producing blasts of two tones, the second tone being of a lower pitch than the first tone.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.