The pulsed field from a triangular aperture mounted in an infinite, rigidbaffle is calculated. The approach of spatial impulse responses,as developed by Tupholme and Stepanishen, is used. By this both the emitted and received pulsed ultrasound field can be found for any transducerexcitation and electro-mechanical impulse response. The continuous wavefield is also readily obtainable through a simple Fourier transform. Thespatial impulse response is calculated without approximation, and thesolution is valid in the half space in front of the aperture for ahomogeneous, non-attenuating medium. The solution can be used in finiteelements programs for calculating fields from arbitrary transducergeometries.