Post-synchronization is the process of adding sound to images after they have been shot and edited into their final offline copy. This can include dubbing of voices, as well as inserting diegetic music or sound effects. It is the opposite of direct sound. The sense of a sound’s position in space, yielded by volume, timbre, pitch, and, in stereophonic reproduction systems, binaural information is created rather than observed, this is why a great sound designer is worth so much, that there judgment and technical skill is good enough to create a realistic sound world from essentially scratch. Used to create a more realistic sense of space, with events happening closer or further away.
The sonic properties of a sound, its timbre, volume, reverb, frequency presence, etc all.have a major effect on a film’s aesthetic. A film can register the space in which a sound is produced or it can be otherwise manipulated for dramatic purposes.