This is a beautiful song composed by Oscar winner A. R. Rahaman. But this is a different type of song and music — having a sort of magical quality around it. At times, it seems to linger on for moments while sometimes it seems to suddenly speed up. This has a profound effect on the listener’ mood. As the speed fluctuates the listener enjoys the variation in emotion that the song and music evoke.
How does the celebrated genius achieve such an effect?
He does so by changing the phase between the song and the music. He purposely avoided synchronous behavior i.e. keeping the song and the music in tune or phase. Note that at times the song seems to lag behind the music. That slows down the speed producing a lingering feeling inside us. Going by the mood of the movie that is exactly the composer wants us to feel — feel the gentle thoughts of love between the hero and the heroine — therefore lingers the sound through the variation of the phase between the song and the music. But at times when the movie is about some action the effect speeds up by allowing the song to lead the music by a certain phase.
This leads us to a profound understanding of waveforms and system behavior.
Phase difference between two waveforms changes a physical effect. Like for example some of the harmonics or waveforms either lead or lag the fundamental frequency thereby slowing down or speeding up movement of the system as a whole.
This happens in all types of systems whether they be electrical, mechanical or electronics. Technically this is called non-synchronous vibrations that we experience frequently in the physical world.
It is worthwhile for analyst to develop a feel for such phase changes in the system. This reveals a lot about system behavior and its causes.
Listening to music and sounds is an easy way by which any analyst can develop this innate skill and hone it to perfection.