Decibels compress a huge range of pressures into a scale that matches how people hear.

The longer version

The scale is logarithmic, so each equal step multiplies pressure rather than adding to it. That is useful because the range the ear handles is enormous: the pressure at the threshold of hearing is tiny compared with the pressure that causes pain, a ratio of millions.

Compressing that span into a small range of numbers keeps charts readable and roughly matches perception, since judging loudness is also closer to multiplication than addition. Zero on the scale is a reference pressure near the hearing threshold, not an absence of vibration. Everyday levels sit in the middle: a quiet room, then speech, then traffic, then machinery.

Where this entry sits

Sound and Music gathers facts about how vibrations move through air and water, how ears turn them into meaning, and how instruments and notation shape what listeners hear. Expect echoes, pitch, volume, acoustics, and the odd silence in between. The full list sits on the Sound and Music page, where every entry is listed in order.