Mach waves generated by turbulent structures in supersonic jet flows have the potential to intersect and coalesce, a process proposed as a significant contributor to acoustic waveform steepening in the near field of a jet and to the noise referred to as crackle [Baars et al., AIAA (2013); Fiévet et al., AIAA (2016)]. Numerical simulations of intersecting waveforms have demonstrated that coalescence can lead to increased steepening that is dependent on intersection angle, waveform duration, and geometrical spreading [Willis et al., AIAA (2022)]. In this study, two simplified experiments involving a spark source in air are examined. The first involves grazing incidence on a rigid plane to model symmetric intersection between waveforms. The second involves intersecting waveforms emanating from side-by-side openings in a 3D-printed enclosure. Measurements of nonlinear evolution were made for the intersecting waveforms produced with each experimental setup and compared with measurements made for one waveform alone. Schlieren images of the coalescing waves allow for comparison of waveform steepening between the two cases without the limitations imposed by microphones. The measurements permit assessment of the extent to which coalescence enhances waveform steepening. [WAW is supported by the ARL:UT Chester M. McKinney Graduate Fellowship in Acoustics.]