1. Apparatus for speech analysis comprising: an analogue to digital converter connected to receive a speech signal to be analyzed, filter means coupled to an output of said analogue to digital converter, for filtering said output to provide a plurality of signals, representative of power intensities in a plurality of frequency ranges in the audio frequency band, median-filtering means, coupled to said filter means, for repeatedly processing a group of successive samples in each said frequency range by multiplying the samples in each said group by respective coefficients and summing the resultants, and smoothing means for repeatedly processing a group of successive outputs of the median-filtering means in said each frequency range by selecting one output according to relative magnitudes thereof.