Spatial sound generation using HRTF created by the use of recursive filters

Generating spatial sound and playing it through headphones is a demanding task, since two important factors, ILD - inter-aural level difference and ITD - inter-aural time difference, need to be taken into consideration. The problem can be solved by the use of head related transfer functions (HRTF) which represent a set of empirically measured functions, one for each spatial direction. The complete reconstruction of HRTF is possible through the use of finite impulse response (FIR) filters with 512 coefficients each. Since the spectrum of HRTF consists of distinctive maximums and minimums, the spectrum could be approximated by the use of resonators and notch filters. The approximation of the complete spectrum (20 Hz - 20 kHz) could be done by the use of six resonators and one notch filter. Our approach to spatial sound generation using HRTF created by the use of recursive (IIR) filters presents a practical and computationally effective solution. It also indicates a way to uniformly model all factors connected to spatial sound perception.