A-weighting is a standard filter used in audio measurements that adjusts the sound to simulate how the human ear perceives it at low volumes.

Our ears do not perceive all frequencies with the same intensity. At low volumes, we are much less sensitive to very low and very high-pitched sounds.

The A-weighting filter mimics this characteristic, attenuating low frequencies (below ≈700 Hz) and high frequencies (above ≈10 kHz) before the measurement is taken. Think of it as a "human hearing mode" for measurement equipment. It focuses on the frequencies that stand out most to us in a quiet environment. This is why A-weighting is the industry standard for measuring very low noise levels, such as the noise floor of microphones, preamps, and audio interfaces. The result, expressed in dBA (decibels with A-weighting), gives us a number that better represents how audible that noise really is to a person. There are other curves, such as C-weighting, which is flatter and used to measure the impact of loud sounds. high, and the K-weighting, used in loudness (perceived intensity) meters for TV and streaming.