anacoustic zone

anacoustic zone

[¦an·ə¦kü·stik ‚zōn]
(geophysics)
The zone of silence in space, starting at about 100 miles (160 kilometers) altitude, where the distance between air molecules is greater than the wavelength of sound, and sound waves can no longer be propagated.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
These heights mark also the bases of the anacoustic zones.