This paper concerns the sound generated at the leading edge of a turbofan blade in an aeroengine when the blade is struck by a convected gust. The gust is localised in space, e.g., in a narrow wake, and is localised in time, producing a highly unsteady impulsive sound field. The relative motion between the blade and the flow is subsonic. The parameter range analysed is the non-compact regime, for which the leading edge may be considered in isolation. Underlying the paper is an analytical result, recently derived by the author, giving an integral for the unsteady three-dimensional sound field everywhere in space, including the near field, when the convected gust is of arbitrary shape.