The presentation concerns a method for tracking cycle lengths in voiced speech. The speech cycles are detected via the saliences of the speech signal samples, defined by the length of the temporal interval over which a sample is a maximum. The tracking of the cycle lengths is based on a dynamic programming algorithm which does not request that the signal is locally periodic and the average period length known a priori. The method has been validated on a corpus of normophonic speakers. The results report the tremor frequency and modulation depth of the vocal frequency of 72 ALS and 8 normophonic speakers.