Defines a triangular mel-filter.
The
MelFrequencyFilterBank2 creates mel-filters and filters spectrum.
A mel-filter is a triangular shaped bandpass filter. When a mel-filter is
constructed, the parameters
leftEdge,
rightEdge,
centerFreq,
initialFreq, and
deltaFreq are given to the
Constructor. The
first three arguments to the constructor, i.e.
leftEdge,
rightEdge, and
centerFreq, 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,
initialFreq and
deltaFreq, 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
scale.
Figure 1 below shows pictorially what the other parameters mean.
Figure 1: A triangular mel-filter.