1. A camera system including at least one camera, at least one microphone to capture sound, and a digital sound recognition system to recognise one or more target sounds in said captured sound, wherein said digital sound recognition system comprises: a sound input coupled to said at least one microphone; program memory storing processor control code; working memory; non-volatile memory for storing one or more statistical models λ of one or more target sounds; and a processor coupled to said sound input, to said working memory, and to said program memory for executing said processor control code, wherein said processor control code comprises code to: input sound data for a sound, the sound data defining frequency domain data, said frequency domain data defining an energy of said sound in a plurality of frequency ranges; receive and store in said non-volatile memory pre-derived statistical model parameters representing a set of statistical models λ representing a set of said target sounds, wherein said parameters characterise said set of target sounds; perform a multiple component decomposition of said sound data by applying a succession of windows to said sound data to construct a time frequency representation of said sound data; calculate, for said set of statistical models λ representing said set of said target sounds, the probability of an observed frequency distribution sequence in said multiple component decomposition of said sound data up to a time T, given the model λ: P ⁡ ( O ❘ λ ) = ∑ i = 1 N ⁢ ⁢ α T ⁡ ( i ) where α t (i) represents the probability of observing said time frequency representation of said sound data up to time t, where i indexes a state of said model defined by mean and covariance values, and wherein P(O|λ) characterises how a frequency distribution of said statistical model λ changes over time; apply a set of threshold values to said probability of an observed frequency distribution sequence in said multiple component decomposition to classify said sound data according to said set of statistical models λ; move a view of said camera in response to classification of said sound data according to said set of statistical models λ to direct said camera towards a recognised target sound.