Localization performance across speaker positions, depicting (a) great circle angle error, (b) local great circle angle error, (c) front–back confusion rate and (d) up–down confusion rate for the No HMD condition. Metric values are reported above each speaker position (white circles), around which Voronoi cells have been drawn to simplify results interpretation. The apparent cell structure asymmetry is a result of the projection mapping inducing distortion at the poles (near ±90° elevation).