1. A method of classifying a signal segment, said method comprising the steps of: (a) receiving a sequence of frame feature data, each of said frame feature data characterising a frame of data along said signal segment; (b) in response to receipt of each of said frame feature data, updating statistical data, characterising said signal segment, with the received frame feature data; (c) receiving a notification of an end boundary of said signal segment; and (d) classifying said signal segment based on said statistical data.