Triangular source geometries defined for near-field pressure calculations. The near-field pressure is evaluated above the vertex A (indicated in bold), and the shape of the triangle (right, acute, or obtuse) is defined by the angle ∠BCA. The height of each triangle is indicated by l, and the bases of the individual right triangles are indicated by s, s1, and s2. The acute triangle in (b) is represented by the sum of two right triangles, and the obtuse triangle in (c) is defined as the difference between two right triangles.