C-Weighting is an audio measurement filter that simulates the human ear's response to high volumes.

Unlike A-Weighting (which mimics our hearing at low volumes), C-Weighting is used to measure high sound pressure level (SPL) sounds, such as at a concert or when calibrating studio monitors.

At high volumes, our hearing becomes much "flatter," meaning we perceive bass, mid-range, and treble frequencies with a more balanced intensity.

The C-weighted filter reflects this, having a nearly straight frequency curve, with only slight attenuation at the extremes of the spectrum (below ≈20 Hz and above ≈10 kHz).

Because it is more representative of our perception at high volumes, the measurement in dBC (decibels with C weighting) is frequently used to assess the sound pressure level in concerts, nightclubs, and to measure the impact of low-frequency noises.