Figure 1: Schematic arrangement of the acoustic shock tube, catenoidal horn, acoustic test fixtures, and the blast probe. The fixtures were sited along the sagittal seam of the fi xture to point to the center of the mouth of the catenoidal horn. The E-A-RCAL, NIOSH ISL fixtures were 1.13 and 1.20 m from the reference point, respectively. The GRAS 67SB blast probe was 1.02 m from the reference point