When working with audio, filters are essential tools for shaping the character of a sound by allowing or blocking specific frequency ranges. The most common filter types are low-pass, high-pass, and band-pass filters.

A low-pass filter allows only frequencies below a certain cutoff point to pass through, removing higher frequencies. This is useful for creating warm, mellow sounds or for reducing harshness in a synth tone. In contrast, a high-pass filter does the opposite: it allows only frequencies above its cutoff point to pass, removing lower frequencies. High-pass filters are often used to thin out sounds, remove muddiness, or make space for other instruments in a mix. A band-pass filter is more selective, allowing only a specific range of frequencies to pass while blocking both the lower and higher frequencies outside this band. This can be used to isolate particular harmonics or create telephone-like effects.

Musically, filters help you sculpt the timbre of instruments, emphasize or de-emphasize certain elements, and create dynamic changes over time. For instance, sweeping a low-pass filter's cutoff frequency can make a synth sound evolve from dark and muffled to bright and clear, a technique often used in electronic music.