Visualization of acoustic pressure and velocity patterns with phase information in the pinna cavities at normal modes

As the peaks of head-related transfer functions are generated by normal modes of the pinna (external ear), the peak center-frequency and the three-dimensional pattern of each normal mode depend on individual pinna geometry. Traditionally, normal modes are visualized mainly in terms of pressure anti-nodes. To better understand the relations between the acoustics and geometry of pinnae, in this study we describe computational methods that extend previous visualizations: (i) by including principal vectors of velocity that reveal patterns of energy exchange between anti-nodes and energy loss to the surrounding air, and (ii) by enabling separate visualization of resonance patterns with common phase-angles. These methods are applied to two individual pinnae: one with a standard set of normal modes, and one whose second and third normal modes are confusable.