Sound filtering... with the Gimp!
Gimp is universally used for image manipulation. However, with a bit of creativity and a couple of tricks, it can also be used as an audio filter! Here is how…
If you are familiar with sound filters, you can skip this introduction. For those of you who don’t know about filters, here is a brief explanation.
A sound, like all signals, is measured in Hz (Hertz). That measure expresses the signal frequency. The lower the measure, the lower the frequency. A filter is a tool that enhances one or more signal frequencies, according to a criterion. In an ideal world, a filter completely suppresses undesired frequencies. Unfortunately, we don’t live in an ideal world.
I will concentrate on a single filter: low-pass. A real low-pass filter is something that receives an input signal and outputs its low frequency components. To be more precise, it attenuates those frequencies higher than a set one (the cut-off frenquency). As you see in figure 1, it just approximates theoretical behavior.