2. The method of claim 1 wherein step (b) comprises grouping adjacent samples with substantially similar upper and lower bounding frequencies as posture spectra.
2. The method of claim 1 wherein step (b) comprises grouping adjacent samples with substantially similar upper and lower bounding frequencies as posture spectra. 3. The method of claim 2 wherein step (b) comprises grouping adjacent samples between posture spectra groups as changing spectra.