decibelA

DecibelA is a proposed logarithmic unit intended to express the magnitude of a quantity that scales with waveform amplitude, in a way that mirrors how the decibel is used for sound pressure and power in acoustics. As of now, decibelA is not a standard or officially adopted unit in physics or engineering, but it appears in theoretical discussions and speculative proposals that seek an amplitude-focused alternative to the traditional decibel.

Definition and formula

DecibelA (symbolized as dB_A) is defined by the relation L_A = 20 log10(A / A_ref), where A is the amplitude quantity of interest and A_ref is a chosen reference amplitude. The factor 20 arises because amplitude is proportional to the square root of power, so a doubling of amplitude corresponds to about 6.02 dB_A. The choice of A_ref determines a zero point, and different fields may select different reference amplitudes, similar to how the standard decibel relies on a reference power or pressure.

Relation to the ordinary decibel

The ordinary decibel expresses ratios of power or intensity (10 log10) or ratios of amplitude-related quantities like pressure (20 log10). DecibelA is intended to be parallel to the amplitude side of that framework but uses its own reference. Because decibelA is not standardized, the exact numerical interpretation can differ if different A_ref values are used. This can lead to inconsistent comparisons across domains if not clearly documented.

Status and considerations

DecibelA has no formal approval from major standards bodies and is rarely used outside exploratory or fictional contexts. A key concern is the potential for confusion with existing terms such as dBA (A-weighted decibel) and with the conventional dB itself. When discussed, decibelA is typically presented with explicit definitions of A_ref and context to prevent misinterpretation.

See also: decibel, A-weighting, logarithmic units, amplitude.