Analysis of DC effects on HRTFs measured with Golay codes: DC blocking Golay codes

The paper analyzes how DC offsets/contaminants typically found in a signal acquisition system can affect head-related transfer functions (HRTFs) which are measured with the Golay code method of acoustic system identification. Loosely speaking, HRTFs are filters which describe the acoustic filtering that the head, torso, and external ear perform on a sound. HRTFs measured from a human or mannequin can be used to simulate spatial sound over headphones and speakers. We develop a model for the Golay-based HRTF system identification process and use typical values of system parameters estimated from an actual HRTF measurement session to show that effects due to DC contaminants are typically very small. From the same analysis, we also prove the surprising theoretical result that there exist pairs of Golay codes which can completely eliminate DC contaminants from the HRTF system identification process, no matter how large these contaminants are. Finally, we exhibit a pair of these "DC blocking Golay codes", and demonstrate how they can be used to construct other, arbitrarily long, "DC blocking Golay codes".