What does 'filtering' entail in audio processing?

Filtering in audio processing primarily refers to the removal or attenuation of specific frequencies from an audio signal. This process involves using various types of filters, such as low-pass, high-pass, band-pass, or notch filters, to control which frequencies are allowed to pass through the audio signal and which are reduced or removed. By applying filters, audio engineers can enhance certain elements of the sound, reduce unwanted noise, or shape the overall tone of the sound.

For instance, if a sound contains too much low-frequency rumble, a high-pass filter can be used to eliminate those unwanted low frequencies while preserving the higher frequencies. The act of filtering is essential in creating a balanced and clear mix in music production, ensuring that each sound occupies its own "space" in the audio spectrum.