Pre-emphasis

Pre-emphasis is the addition of equalization and/or dynamic processing to an audio track with the expectation that it will be de-emphasized upon playback. Pre-emphasis is often a component of noise reduction schemes, the oldest and most common being the Academy curve.

Mono optical soundtracks must be pre-emphasized by boosting their high frequency content and then de-emphasized by the Academy EQ curve during playback in a theater. This de-emphasis will bring the audio content back to its original EQ while significantly reducing the noise inherent in film playback.