Any medium through which the music signal passes, whatever its form, can be regarded as a filter. However, we do not usually think of something as a filter unless it can modify the sound in some way.
This section is devoted to the concept of filtering. It examines the basic idea, and defines some basic filter types. It is important to remeber that actual filters, either digital or analog, behave in ways that are different from the ideal. These diffences can be musically advantagous or not, but should be accounted for in musical applications.
Some basic filter types:
Low-pass filter - Low frequencies are passed, high frequencies are attenuated.
High-pass filter - High frequencies are passed, Low frequencies are attenuated.
Low shelf and high shelf filters
Band-pass filter - Only frequencies in a frequency band are passed.
Band-stop filter - Only frequencies in a frequency band are attenuated.
All-pass filter - All frequencies are passed, but the phase of the output is modified.
