effect on the over all improvement provided by aperture 42 in sustaining the amplitude of the waves as discussed below as previously mentioned the traveling sound waves are always moving in the general horizontal direction towards ends 18 20 with each reflection of the wave its amplitude is somewhat diminished or weakened due to energy dissipating caused by dispersion or scattering of the waves excursions from its natural form the degree or amount of dispersion depends upon the angle of wave reflection with respect to the general horizontal direction of wave movement thus by providing substantially horizontal surfaces 60 62 64 66 that substantially trap the waves within corridor 44 the present perforated acoustic transport member 12 minimizes wave dispersion fig6 is a graphic illustration generally showing a measure of improvement in minimizing wave dispersion for retaining the intensity of sound waves propagating through the perforated acoustic transport member 12 compared to known member 12a in the graph the solid line 68 depicts a wave form produced from passing through the known acoustic member 12a disclosed in prior application ii the dashed line 70 represents a wave form obtained using the perforated acoustic member 12 as will be explained below the configuration of the two acoustic members 12 12a are identical except for the aperture 42 feature also the impact point selected for producing the wave forms 68 70 shown and its.