4. Estimation of Spectral Envelopes

Estimation is the task of computing the spectral envelope of a signal. First, the
general requirements for this step will be introduced in
section 3.1, then the estimation methods LPC,
cepstrum, and discrete cepstrum will be described in the following
sections 3.2-3.5. These descriptions will
proceed from a non-formal introduction
(*what the algorithm does*) to a detailed formal development
(*how it is done*), in some cases followed by a definition of the
class of the algorithm in the taxonomy of signal processing systems.
For the discrete cepstrum method, an evaluation will be presented in
section 3.6.

As the methods for spectral envelope estimation described in this chapter all have their strong and weak points, depending on the signal and the needs of the user, all methods have been implemented in the spectral envelope library, to keep it as flexible as possible.

- 4.1 Requirements
- 4.2 LPC Spectral Envelope
- 4.3 Cepstrum Spectral Envelope
- 4.4 Discrete Cepstrum Spectral Envelope
- 4.5 Improvements of the Discrete Cepstrum Method
- 4.6 Evaluation of Discrete Cepstrum Estimation