Cweighting

Cweighting, more commonly written as C-weighting, is a standard frequency weighting used in acoustics to characterize sound pressure levels. It is defined as one of the weighting networks applied to microphone signals in sound level meters, intended to reflect human hearing at moderate to high sound levels. Compared with A-weighting, C-weighting yields a relatively flatter response over much of the audible spectrum, providing less attenuation of low frequencies and a smoother overall curve.

In measurement practice, C-weighting is realized as a fixed analog or digital filter that is applied to the recorded sound signal. The filtered signal is used to compute quantities such as the C-weighted equivalent sound level (L C) or C-weighted peak levels (L C peak), depending on the measurement needs. Because it emphasizes higher frequencies less aggressively than A-weighting, C-weighting is more sensitive to mid- and high-frequency content while allowing more low-frequency energy to influence the result.

C-weighting is commonly used for assessing louder or broad-spectrum noise sources where a flat or gently sloping response is desirable, such as certain types of equipment noise, concerts, or aircraft-related noise, and for general loudness assessments that do not require the steep attenuation of low frequencies characteristic of A-weighting. It is not typically used for regulatory compliance that targets hearing protection, where A-weighting is more common, nor for precise loudness matching at low levels.

Standardization: The C-weighting curve is specified in international standards for sound measurement, including IEC 61672 and ISO 1996, ensuring consistency across instruments and laboratories.