I recently encountered two examples where an increase in volume of music portends something important is happening:
-In watching The Truman Show for the umpteenth time, I noticed at one point director Cristof points to the live pianist to increase the music. The musician obliges and the melancholy music swells. (Bonus: you can see composer Phillip Glass playing piano in this scene as Truman sleeps.)
-In a chapel service, the organist played a quiet piece underneath a prayer, but as soon as the prayer ended, the volume and activity increased as the congregation moved to singing together.
This musical signaling is common in live events, religious services, television and film, and elsewhere. When the music increases in volume and/or activity, something important is happening. It is a cue to the events unfolding in front of the participant or the viewer.
Is it emotional manipulation? Can we be pushed in directions we may not even be aware of just by the musical vibrations around us? Perhaps. Yet, humans have done this for centuries and millennium as music has a long and rich history not just as an individual activity but a collective tissue and performance where tone, volume, timbre, and more contribute to life together.