The decibel, abbreviated as dB, is a unit of measurement used to express the intensity of sound waves. It is a logarithmic scale that compares the sound pressure level (SPL) of a sound to a reference level. The reference level is typically the lowest level of sound that the human ear can perceive, which is about 20 microPascals (μPa).

The decibel scale is commonly used in a variety of fields, including physics, engineering, and acoustics. In the context of sound, it is used to describe the loudness or intensity of a sound wave. For example, a whisper may measure at around 30 dB, while a rock concert can reach up to 110 dB.

The human ear is capable of perceiving sounds ranging from 0 dB (the threshold of hearing) to 120 dB (the threshold of pain). Exposure to sounds above 85 dB for prolonged periods can cause hearing damage, while exposure to sounds above 120 dB can cause immediate and permanent hearing loss. The decibel scale is an essential tool for measuring and regulating sound levels to prevent hearing damage and other negative health effects.