Fast multipole boundary element method to calculate head-related transfer functions for a wide frequency range

Area of Science:

• Acoustics
• Computational physics
• Bioacoustics

Background:

• Head-related transfer functions (HRTFs) are crucial for understanding spatial sound localization.
• Traditional boundary element method (BEM) simulations are computationally intensive, limiting HRTF calculations to below 10 kHz.
• Accurate HRTF modeling is essential for immersive audio and virtual reality applications.

Purpose of the Study:

• To enhance the frequency range of head-related transfer function (HRTF) simulations using computational methods.
• To investigate the efficacy of coupling the fast multipole method (FMM) with the boundary element method (BEM) for HRTF calculations.
• To assess the impact of mesh resolution and additional anatomical features on simulation accuracy.

Main Methods:

• The fast multipole method (FMM) was integrated with the boundary element method (BEM) for HRTF computation.
• High-resolution meshes (over 70,000 elements) were utilized for detailed head and pinnae modeling.
• Simulations were validated against acoustically measured HRTFs, with and without shoulder inclusion.

Main Results:

• The FMM-coupled BEM successfully calculated HRTFs up to 35 kHz, a significant increase from conventional BEM limits.
• Congruence with measured HRTFs was good below 7 kHz, improving with the addition of a shoulder mesh for vertical localization cues.
• Mesh size reduction by 5% notably degraded spectral cue representation, while temperature and mesh perturbations had minimal effects.

Conclusions:

• The fast multipole method (FMM) shows significant promise for extending the frequency range of head-related transfer function (HRTF) simulations.
• Accurate HRTF modeling requires sufficient mesh resolution and consideration of surrounding anatomical structures like shoulders.
• Further research into FMM-coupled BEM can advance spatial audio technologies and psychoacoustic studies.