optical sound

American

noun

Movies.

sound recorded on and subsequently played back from an optical or photographic soundtrack, as opposed to a magnetic soundtrack.

optical sound British

noun

sound recorded in the form of a photographic image on cinematograph films

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of optical sound

First recorded in 1930–35

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023