**3.1.2 Step 2: Adjustable resolution analysis**

In the above explained step, an approximation to the formantic frequencies was obtained. As it will explained in next head, the resolution obtained with this approximation, though it is better than the one obtained with conventional methods, may not be enough for some environments.

In order to achieve a finer resolution, an adjustable resolution analysis was designed. The scheme of this analysis is shown in Figure 1. The core idea of the designed technique is to obtain a higher resolution in the previously detected bands by dividing the selected nodes and their adjacent ones.

The main reason of using narrower bands is that energy in wavelets packet spreads among various adjacent nodes, the solution to this problem is to divide the spectrum in such narrow bands that the energy of the formant locates in only one node.

As it can be seen in Figure 1 the first step of the algorithm consists on splitting the approximated formantic bands and their adjacent as many times as necessary. Secondly, the energy of each node is calculated again and the maximum value located, this value indicates formant location.

The main advantage of this method is that it is possible to save a lot of computational load but preserving a high accuracy level at the same time. For example, if an 8 level basic tree is to be taken and its formantic nodes are expanded two levels, it is possible to obtain a 10 level resolution by consuming an 8 level computational load.
