1 The wavelet transform - International Computer Science Institute

Competing subjectively
FIGURE 81. The base viewer used to select a certain basis from the wave packet library of bases. This decomposition
has eight levels. The bottom most level is not shown, but is always used when no higher level was selected.
transform and the wave level transform. The selected basis of figure 82 corresponds to a wavelet
basis at the sixth decomposition level. Using this selection as a fixed basis for the wave
packet transform calculates exactly the same transform as a simple wavelet transform down to
the sixth decomposition level. A wave level transform is calculated when a complete row of
1 2 3
FIGURE 82. The base viewer used to select the wavelet basis at the sixth decomposition level.
rectangles in the base viewer window is activated. In respect to computational complexity these
simulations are much more expensive than the original transform algorithms.
When wave packet transforms are performed in the best base mode, the buttons (1) + (2) allow
to keep track on the best base choice. Pressing the now-button (1) captures and displays the
chosen basis of the last wave packet transform. With the history-button (2) the frequency each
of the rectangle components was chosen to belong to the best basis is illustrated. According to
the number of times recently used the rectangle is colored in different red shades (see
FIGURE 83. The base viewer illustrates the frequency with which a rectangle was chosen to belong to the best basis.
figure 83). This will allow statements about bases that are a preferred choice from the library of
wave packet bases. The clear button (3) resets the state of the base viewer - all rectangles are
deactivated.
The auditory results fulfilled the expectations we had after the investigations about the capture
of signal power, but were also surprising in some points. It is very difficult to make any statements
about the quality of the audio signal in the self hear mode. The test persons - who simul-
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