General disagreement or conflict:
* Strife
* Disagreement
* Conflict
* Friction
* Contention
* Quarrel
* Feud
* Bickering
* Tension
* Chaos
* Turmoil
For disagreement in music:
* Dissonance
* Cacophony
* Harmonic clash
For a lack of harmony:
* Disunity
* Division
* Disarray
* Separation
* Fracture
The best synonym to use depends on the specific situation and the nuance you want to convey.