dB Calculator

Notes & formulas 

1. Energetic addition

Combines independent sound levels by summing their energies rather than their dB values.

Formula

2. Energetic subtraction

Removes a known component from a total level (e.g. background noise).

Formulas 

3. Energetic average (reported in dB)

Averages sound levels in the energy domain and reports the result in dB.

Formulas

4. Frequency weighting (A/C/Z)

Convert between dB(Z), dB(A) and dB(C) using the standard frequency corrections A(ƒ) and C(ƒ).

Conversions

C = Z  + C(ƒ)
Z = A - A(ƒ)
Z = C - C(ƒ)

A/C/Z weighting table
(1/3-octave)