tone reversal

tone reversal

[′tōn ri‚vər·səl]
(communications)
Distortion of the recorder copy in facsimile which causes the various shades of black and white not to be in the proper order.
References in periodicals archive ?
This is the origin of the tone reversal under "metatonie douce", which yielded a rising tone in Lithuanian but a falling tone in Latvian (cf.