CW audio filters are an essential tool in signal processing. They are used to modify the frequency response of an audio signal, allowing for the removal or enhancement of specific frequencies. These filters can be implemented in both analogue and digital domains, with each having its own advantages and disadvantages. Analogue filters are typically used in audio equipment such as mixers and amplifiers, while digital filters are commonly found in software applications and digital audio workstations. There are various types of audio filters, including low-pass, high-pass, band-pass, and notch filters.