Are the voice and background tracks merged together when filming hollwood movies? When we watch a movie we can hear background music and voices of actors. We also hear sound effects. When we watch a DVD movie the voice and background music merged inside a language track such as English language audio track. Audacity is program used to mix voice-overs and music. It is hard to create an audio track in another language if there is not a separate sound track. It is easy to dub a movie when there is a sound track.  


When creating Hollywood movies, are there separate vocal track and a music track?
Is there a separate track for sound effects?
How do you mix voice and music tracks and convert it into a language track?
What is the software used to mix the tracks in question 3?
What is an original sound track (OST)?
Is the original sound track (OST) used when dubbing a movie?


Thanks in advance.
To answer only the first part, film sound is often split into three parts: music, effects, and dialog. This allows dialog to be replaced for dubbing. This isn't a hard-and-fast rule but it's the general way it's been done for a long time. 

This is not how the sound is released, though. For release these are combined into a theatrical mix of two or more (for surround) channels, so the original three-track mix is no longer in play.