Sound in Thrillers

Some of the sound features which appear in thrillers are:
.Music
.Sound Effect
.Diegetic sound
.Non-Diegetic sound
.Noise
.Pitch
.Added effects - Heartbeat

Asynchronous is sound which is opposite to the mood which is in the scene.
Synchronous is sound which is in sync with the mood which is relevant to what is going on in the scene. It's also diegetic sound.

What makes a good thriller soundtrack?
.Suspense
.Tension - the building of tension
. High pitched music
Mixing of pitch
.Dramatic
.Crescendo
.Instruments
.Out of tune instruments
. Change of pace
. Enhances the emotion of the scene
.Lots of contrast
.The music tends to be in a minor key
Strings (high pitched)
.Creates a sense of enigma - sense of mystery