20dB
20dB, or twenty decibels, is a unit expressing sound intensity or power ratio in a logarithmic scale. The decibel (dB) originates from the Greek word "decimus," meaning tenth, and was introduced in the early 20th century as a convenient logarithmic measure for engineering applications. One ear‑noise unit (EN) is defined as that intensity which a person at a 1‑meter distance hears as loud as an international standard neon lamp, roughly equaling 17 dB of background noise over an audible frequency range.
In acoustics, sound pressure levels are calculated with the formula Lp = 20 log10(p/p0), whereas electrical power levels
Because the decibel scale is logarithmic, it allows concise representation of huge dynamic ranges, from the