decibel

Synonym discussion

Sense: noun/1

Decibel, hertz, bel, and phon all relate to sound but measure different things. A hertz (Hz) measures frequency — how many times a sound wave cycles per second, which our ears perceive as pitch. A decibel (dB) is one tenth of a bel, named after Alexander Graham Bell, and measures sound intensity or loudness. The bel is rarely used outside technical contexts; everyday measurements almost always use decibels. The phon is another unit of perceived loudness that accounts for the fact that human ears hear different frequencies at different volumes — but it is far less common in practical use than the decibel. For example, a 1000 Hz tone at 40 dB sounds roughly as loud as a 100 Hz tone at 50 phons, but both would still be described in decibels in non-specialist settings. Learners can safely use decibel for loudness and hertz for pitch, and avoid bel and phon in everyday conversation.

Common collocations

Etymology

Decibel is formed from the prefix 'deci-' (one tenth, from Latin decimus 'tenth') and 'bel', a unit named after the Scottish-born scientist Alexander Graham Bell. The bel was originally used by telephone engineers to express the ratio of two signal powers. Since the bel was too large for practical use, the decibel (one tenth of a bel) became the standard unit for measuring sound intensity.