notch filter

This term is a technical specification used primarily in electrical engineering, audio processing, and signal analysis. It describes a high-precision tool designed to eliminate a single, problematic frequency—such as electrical mains hum—without distorting the surrounding spectral content. This distinguishes it from a low-pass or high-pass filter, which removes entire ranges of frequencies.

In practical application, the term is used in both hardware (analog circuits) and software (digital signal processing). Because it targets a specific "notch" in the frequency response, it is characterized by its selectivity and narrow bandwidth, making it indispensable for cleaning audio recordings or stabilizing sensor data in industrial environments.