Production of 3D sound for virtual auditory space needs interpolated head related impulse responses (HRIRs), due to limitation of real-time system for storing HRIR measurements. Fortunately, interpolation of HRIRs can reduce much cost and effort in measuring many HRIRs. This research analyses three interpolation techniques, namely bilinear rectangular, bilinear triangular, and tetrahedral by using PKUIOA HRTF Database. Bilinear triangular interpolation has been applied to estimate a target HRIR from 3 surrounding measured HRIRs that form a triangle. Accordingly, bilinear rectangular interpolation uses 4 surrounding rectangular measured HRIRs. These geometrical approaches compute weights from relative angular distances of a target HRIR from measured HRIRs. Tetrahedral interpolation, in other hand, is an interpolation technique in 3D using barycentric weights. An optimal framework in obtaining estimated HRIRs is proposed here by interpolating minimum phase HRIRs using tetrahedral interpolation.