Synchronisation defines the way in which a sound is used in production. Original sound material is considered to be 'synchronised' when it has been mixed or rendered with other audio-visual material. The resulting file is in accordance with the licensing agreement and can be distributed in various ways (e.g. cinema, TV, internet, CD) without incurring further duties.
Also part of the synchronisation law are live events that make use of pre-recorded audio elements in the mix (e.g. stage productions, object tracks in a 3D audio mix). There is, however, one group of applications that is not covered under synchronisation law. Any usage that is dependent on the interaction of the user to trigger it (e.g. doorbell, toys, sounds in smartphone apps) is included in that group. This kind of usage requires an extended license (a so-called mechanical license).