Elemental normalized level difference

In the chaos of the sounds surrounding us – the rustle of the wind, the buzz of the street, or the cracks – our brain has an extraordinary ability to catch order. It is this order that makes us perceive some sounds as "musical," pure, and pleasant, while others are perceived as formless noise. The key to this harmony is repetitiveness, which is a feature that defines periodic sound.

When we go outside after a night of snowfall, we often immediately notice that the world has become not only brighter but also surprisingly quiet. The sounds that usually dominate — traffic, the rumble of tires, the sound of footsteps — seem muted, softer, as if absorbed by the surroundings. This characteristic "winter hush" is not magic, but physics.

When we hear noise coming from the neighbor, we instinctively think that "the walls are thin." But sound has a remarkable ability to travel not only through the air. It can turn concrete, steel, and even wood into highways that reach the farthest corners of a building, often bypassing our attempts to soundproof. This sneaky traveler is material sound.