Defines a triangular mel-filter.
creates mel-filters and filters spectrum.
A mel-filter is a triangular shaped bandpass filter. When a mel-filter is
constructed, the parameters
are given to the
first three arguments to the constructor, i.e.
, specify the filter's
slopes. The total area under the filter is 1. The filter is shaped as a
triangle. Knowing the distance between the center frequency and each of the
edges, it is easy to compute the slopes of the two sides in the triangle -
the third side being the frequency axis. The last two arguments,
, identify the first
frequency bin that falls inside this filter and the spacing between
successive frequency bins. All frequencies here are considered in a linear
Figure 1 below shows pictorially what the other parameters mean.
Figure 1: A triangular mel-filter.