Use of sound in our own opening sequence

In the opening to our thriller film we plan to use a variety of both diagetic and non diajetic sound effects as well as soundtracks.
The possible sound effects we will need include:
- a phone ringing,
- a disconnected phone tone,
- distant birds ,
- gun sound effects,
- voice mail,
The sound tracks we will use are:
- An eerie, mournful and slow sound track at the beginning of the sequence, behind the titles and shots of the girl suffering,
- An upbeat and cheery peice of music for the scene where the oblivious mother is cleaning in the kitchen,
- Followed by a very contrasted soundtrack to accompany the traumatic scene with the girl and the two men after she leaves a message for her mother.