“The Good, The Bad and The Ugly” has its main theme, which is used as the leitmotif for all three of its protagonists. Different sections from the song are used for each character, utilizing different instrumentation to represent their characters’ central ideas and the like.
The Sound Editor works alongside the Editor in terms of adding and manipulating sound in concordance with the film itself. Their jobs will lean toward the technical aspects of sound, syncing, ADR, etc.
This isn’t the only job involved with sound in film however, as the Sound Mixer does the post-production and creative processing involved with the film’s audio; they will work with blending the score into scenes, and specific effects and processing of sound, like a music producer.
The sound editor is responsible for all of a film’s sound elements, including dialogue, sound effects, and automated dialogue replacement and more. Once this has been done the sound mixer can start to work.
The sound mixer decides how an audience hears everything in a film. The sound mixer must decide what elements to emphasize and which to tone down. Like for example the score getting louder to emphasis an emotion.
In layman’s terms, sound editing is about collecting the sounds needed for a film. Sound mixing refers to what is done after they are collected. The sound editing category used to be known as sound effect editing, which is actually the more apt name.