SSP stands for Speech Signal Processing. It is a fairly small package written in python. Its functionality is similar to tracter, with some overlap and some additional capabilities. In particular, SSP contains a parametric vocoder, a pitch extractor and feature extraction for ASR.
The pitch extractor implemented in SSP is that described in the following paper: A Simple Continuous Pitch Estimation Algorithm
The source is available on GitHub at https://github.com/idiap/ssp