A source-directivity impact assessment for an angle-error model used to compute free-field sound power over a cylindrical enveloping surface

An angle-error model was previously shown to accurately predict the necessary sound power correction term for omnidirectional sources using only a few readily-obtainable inputs related to the geometry of the source and the enveloping measurement surface. This paper assesses the validity of that predictive regression equation when the omnidirectional assumption is removed, and the effects of a directional source are examined through modeled analysis and empirical study. The modeling work modified the initial ray-tracing model used to incorporate source directivity. The empirical aspect of this paper compares the modeled angle error to that of a directional speaker source over a range of positions using a cylindrical measurement surface in accordance with ISO 3744 and ISO 7779. The corrected sound power levels were compared to the measured sound power levels of the source per ISO 3741 direct and comparison methods.