input file : source soundfile
output file : destination soundfile (when marked)
or result.wav (for unregistered files)
processing mode : local or global
The lowpass filter (low-frequency shelving filter) can be used to attenuate the high-frequency components of the signal. The filter has two adjustable parameters.
The cutoff frequency (expressed in hertz) determines the passband of the filter, i.e. the frequency range [0 Hz,cutoff frequency] in which the signal is (almost) not modified. The cutoff frequency must be in the range [20 Hz , 0.45(sampling frequency)]
The bandpass attenuation coefficient (expressed in decibels per octave) decides upon the 'sharpness' of the filter - the larger the value of this coefficient, the steeper becomes the 'cut' at the cutoff frequency. Sharper filters are more complex, and hence they result in longer processing times.