Comparison of direct and indirect perceptual head-related transfer function selection methods.

Brian F G Katz,Markus Noisternig,Franck Zagala

doi:10.1121/10.0001183

Abstract

When a personalized set of head-related transfer functions (HRTFs) is not available, a common solution is identifying a perceptually appropriate substitute from a database. There are various approaches to this selection process whether based on localization cues, subjective evaluations, or anthropomorphic similarities. This study investigates whether HRTF rankings that stem from different selection methods yield comparable results. A perceptual study was carried out using a basic source localization method and a subjective quality judgment method for a common set of eight HRTFs. HRTF rankings were determined according to different metrics from each method for each subject and the respective results were compared. Results indicate a significant and positive mean correlation between certain metrics. The best HRTFs selected according to one method had significant above-average rating scores according to metrics in the second method.

Highlights

In the fields of spatial hearing and spatial audio reproduction, headphone-based techniques have been extensively investigated and used (Begault, 1994; Blauert, 1996; Rumsey, 2012)
The term grading (G) is employed here for normalized values between zero and one that rate each head-related transfer functions (HRTFs) according to the metrics described below while preserving the interval relations, while ranking (R) is used to regard only the ordinal relation of the grading between HRTFs
To highlight eventual correlations between the results of each method, HRTF gradings and rankings were established for each subject with respect to different metrics: mean unsigned lateral error, mean unsigned polar error, mean great circle error, and confusion rate for the localization method and horizontal plane score, median plane score, and both planes score for the quality evaluation method

Summary

Introduction

In the fields of spatial hearing and spatial audio reproduction, headphone-based techniques have been extensively investigated and used (Begault, 1994; Blauert, 1996; Rumsey, 2012). Field into binaural signals such that the sound pressure at each eardrum as produced by the headphones is perceptually equivalent to the original circumstances This equivalence implies the presence of morphologically determined acoustic cues, such as the low-frequency interaural time difference (ITD), high-frequency envelope ITD, and, to a lesser extent, highfrequency interaural level difference (ILD) for lateral source direction localization, the high-frequency ILD for auditory distance perception of near-field sources outside the median plane, and monaural cues that help discriminate direction on a cone of confusion (i.e., constant ITD or ILD contour; see Katz and Nicol, 2019, Fig. 11.1) through spectral indices.

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Results

Conclusion