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optical sound

American  

noun

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


optical sound British  

noun

  1. 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

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

The conventional "optical" sound track on the edge of the film is replaced by a "sound-stripe" of magnetic material, as in a tape recorder.

From Time Magazine Archive