3D sound is a new trend in various media, such as movies, video games, and musicals. Interpolated head-related transfer functions (HRTFs) are a key factor in its production, dueto real-time system limitations in storing measured HRTFs. In addition, theinterpolation of HRTFs can reduce the need to measure a large amount of HRTFs andthe associated effort. In this research, we used the PKU-IOA HRTF Database andcovered three interpolation techniques, namely bilinear rectangular, bilineartriangular, and tetrahedral. Bilinear interpolations can be used to computeweights in interpolating measured HRTFs in a linear fashion, with respect toazimuth and elevation angles. Such interpolations have been proposed for threemeasurement points that form a triangle or for four measurement points thatform a rectangle, surrounding the HRTF at a desired point. These geometricalapproaches compute weights from a distance of the desired point from eachmeasurement point. Tetrahedral interpolation, meanwhile, is a technique forHRTF measurements in 3D (i.e. azimuth, elevation, and distance) using barycentric weights. Based on our experiments, 3D tetrahedralinterpolation results in the best average mean square error (MSE) of 3.72% for minimum phase head related impulse responses (HRIRs) and best average spectral distortion (SD) of2.79 dB for magnitude HRTFs, compared to 2D bilinear interpolations (i.e.rectangular and triangular interpolation). Regarding the latter, bilinearrectangular interpolation generally performs better than the triangularvariety. Additionally, the use of minimum phase HRIRs as input data results inmore optimal interpolated data than magnitude HRTFs. We therefore propose anoptimal framework for obtaining estimated HRIRs by interpolating minimum phaseHRIRs using tetrahedral interpolation. Such HRIRs have been simulated toproduce virtual 3D moving sound in a horizontal plane with a difference of 2.5oof azimuth angle. The simulated moving sound that is heard moves naturally in aclockwise direction from an azimuth angle of 0o to 360o. |