The pursuit of generalisation presented is extensive but not exhaustive, and future research can aim to extend the acoustic feature space, and to produce statistics using a larger population of cells under less varied conditions. A shift in focus is recommended, away from demonstrating the correlation of specific acoustic features to states of a single cell, and towards demonstrating the consistency of those features in a population of multiple cells. The machine learning approaches put forward in this work should be useful to this end. Alternative statistical metrics of similarity may also be used.