The Perceptual Contribution of Pinna Related Transfer Function Attributes in the Median Plane

This thesis describes the work carried out to investigate the perceptual effects of pinna notches in median plane sound localisation. Literature regarding sound localisation and the effects of the pinnae is outlined before a thorough description of the measurement procedure to obtain individualised HRTFs (head related transfer function) is given. HRTFs of three subjects were recorded at seven different positions in the median plane (0˚, 30˚, 60˚, 90˚, 120˚, 150˚ and 180˚). Two experiments were carried out using the measurements. The first consisted of reducing the magnitude of, and removing pinna related notches in the HRTFs to identify the perceptual effects of notch manipulation in both virtual reverberant and pseudo-anechoic conditions. Results for the first experiment show a great deal of variation between subjects, although it can be said that pinna notch filling is most detrimental to median plane localisation in the BRIR (binaural room impulse response) condition and often results in hemispheric reversals and localisation inconsistencies. The second experiment compared localisation abilities of binaurally presented sound sources in reverberant conditions to that of binaural pseudo-anechoic conditions, using real room loudspeaker localisation as a reference. Results from the latter experiment show that virtual localisation in the median plane is better in the presence of reverberation, and that subjective experience in a listening room may influence this result.