The present invention isolates respiration phases in an acoustic signal using trend analysis. Once respiration phases are isolated, they are used to estimate respiration parameters. An exemplary method comprises receiving an acoustic signal recording body sounds identifying candidate peaks at maxima of the signal identifying candidate valleys at minima of the signal selecting significant peaks from among the candidate peaks using heights of the candidate peaks selecting significant valleys from among the candidate valleys using heights of the candidate valleys detecting silent phases in the signal based at least in part on rise rates from the significant valleys isolating respiration phases in the signal based at least in part on the significant valleys and the silent phases calculating respiration parameter estimates based at least in part on the respiration phases and outputting the respiration parameter estimates.
