Human vision, hearing and other senses are not absolute measurement devices. They compare the difference between a reference and the tracked signals, and it changes over time. ​The hearing system registers sounds and requires some time to assess what they are. It then starts to track the changes giving less importance (losing interest) to long and sustained signals with no change. ​It adapts to the surrounding (residual) background and concentrates on the constant changes in signal properties.

 

Motion or flashing lights attract your vision in this exact same way. This phenomenon allows you to follow a conversation between two people in a noisy environment or listen to the voice of a singer undisturbed by a busy musical piece. It is so natural to us that in your office you realize how noisy it is only when the noise stops.​ If the background is quiet the following sound appears louder and clearer. Anything different from the pitch-black background attracts your attention. Or if your hearing has adapted to a residual noise you start losing information (your brain does not pay attention to it). To make an analogy it is like increasing the contrast in a picture by darkening the background instead of increasing the brightness. The bright light will blind you and you will not see better, but removing the strenuous light makes your reference (black) stable and the picture becomes more vivid and sharp. It's like watching a movie in the cinema with the ambient lights on or off.

 

Let us put this in the context we are interested in. Music is written with notes and pauses that represent sounds and SILENCE. The quality and quantity of silence in between notes is just as important as the pitch and timbre in the notes themselves. ​It is rather complex why we have all those artifacts in our precious music through the reproduction chain but it is immediately apparent when they are reduced, and simply amazing when they are almost gone. Serenity and expressiveness come to mind when you experience it. It just sounds right.