Psychophysical customization of directional transfer functions for virtual sound localization

The accuracy of virtual localization when using nonindividualized external-ear transfer functions can be improved by scaling the transfer functions in frequency [Middlebrooks, J. Acoust. Soc. Am. 106, 1493–1510 (1999)]. The present letter describes a psychophysical procedure by which listeners identified appropriate scale factors. The procedure ran on nonspecialized equipment, took as little as 20 min, and could be used successfully by inexperienced listeners. Scale factors obtained from the psychophysical procedure approximated factors computed from acoustical measurements from individual listeners. Roughly equivalent virtual-localization accuracy was obtained using scale factors derived from acoustical measurements, from the psychophysical procedure, or from listeners’ physical dimensions.