0dB

0dB is a logarithmic unit used to express ratios of power or intensity, commonly in audio, radio, and telecommunications. The symbol “dB” stands for decibel. When a sound level is designated as 0 dB, it refers to a reference level against which other levels are compared. In sound level meters, 0 dB typically represents the threshold of human hearing, roughly 20 µPa for 1 kHz in free-field conditions. In electronic systems, 0 dB indicates that the output level equals the input level, with no change in amplitude.

In audio production and broadcasting, the term “0 dBFS” (decibels relative to full scale) is used to designate the maximum digital level that a recording or playback system can represent. Values approaching 0 dBFS risk clipping, whereas signals below –6 dBFS are often considered safe for mixing. In reference to loudness units, the loudness unit “LUFS” (loudness units relative to full scale) is measured with respect to 0 LUFS as a standard for perceived loudness across media.

The decibel scale is derived by the formula 10 log10(P1/P0) for power ratios or 20 log10(A1/A0) for amplitude ratios, where P0 and A0 are reference power and amplitude. Thus, 0 dB means a ratio of 1:1; any positive value indicates amplification, while negative values signify attenuation. Because the scale is logarithmic, a change of 3 dB approximately doubles or halves the power, making it useful for expressing wide dynamic ranges.

Historically, the decibel was introduced in the early 20th century to simplify the handling of large signal ranges. It remains essential in audio metering, network engineering, and acoustic studies, providing a common language for expressing signal strength, loudness, and attenuation.