sound level meter
An electrical instrument for measuring sound pressure levels. To compensate for the way we perceive the relative loudness of different frequencies of sound, there are three networks: A, B, and C. These networks weight the recordings for different frequencies and combine the results in a single reading. The A-network scale, in DBA units, is most commonly used since it discriminates against the lower frequencies, as does the human ear at moderate sound levels. (Ching, 1995)