HRTF (Head-Related Transfer Function) Spatial Audio and Pinna Diffraction: Fundamental Mechanics and Deep Mathematical Modeling

[Chase Allen]

I’ve spent the last few months reverse-engineering how competitive FPS titles handle spatial cues, and I’m trying to understand the actual mechanics behind HRTF personalization rather than just the marketing. When you’re playing at a high level, the difference between nailing an enemy’s position through a wall and missing it comes down to subtle binaural processing. My core question is around the mathematical modeling of pinna diffraction—specifically, how the spectral notches and peaks introduced by the outer ear’s geometry get captured and stored in an HRTF database. For someone building a personalized profile, what’s the most reliable measurement approach: ear-swept probe-microphone capture in an anechoic environment, or can you get away with a smaller sampling grid around the pinna where the highest spatial gradients occur?

On the ITD versus ILD side, I’m curious where the crossover happens in terms of perceptual dominance. I understand low-frequency phase-based ITD and high-frequency head-shadow ILD, but the transition region around 1.5-3 kHz is where things get murky because of the wavelength-to-head-size ratio. When personalizing an HRTF, how do you weight the interaural cues against the spectral shaping for elevation, since most people report that spectral cues are far more critical for up-down discrimination? And is there a practical threshold where individualized HRTF measurements actually beat generic databases in a blind localization test, or are we still in the regime where generic profiles are “good enough” for most listeners?

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