Deriving played trumpet directivity patterns from a multiple-capture transfer-function technique

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The directional radiation patterns of musical instruments have long been defining characteristics known to influence their perceived qualities. Technical understanding of musical instrument directivities is essential for applications such as concert hall design, auralizations, and recording microphone placements. Nonetheless, the difficulties in measuring sound radiation from musician-played instruments at numerous locations over a sphere have severely limited their directivity measurement resolutions compared to standardized loudspeaker resolutions. This work illustrates how a carefully implemented multiple-capture transfer-function method adapts well to played musical instrument directivities and achieves compatible resolutions. Comparisons between a musician-played and artificially excited trumpet attached to a mannikin validate the approach's effectiveness. The results demonstrate the trumpet's highly directional characteristics at high frequencies and underscore the crucial effects of musician diffraction. Spherical spectral analysis reveals that standardized resolutions may only be sufficient to produce valid complex-valued directivities up to nearly 4 kHz, underscoring the need for high-resolution, played musical instrument directivity measurements.