The contribution of head motion cues to localization of low-pass noise

Abstract

Localization of low-pass sounds was tested in relation to aspects of Wallach's(1939Wallach's( , 1940 hypotheses about the role of head movement in frontJback and elevation discrimination. With a 3-sec signal, free movement of the head offered only small advantage over a single rotation through 45°for detecting elevation differences. Veryslight rotation, as observed using a 0.5-sec signal, seemed sufficient to prevent front/back confusion. Cluster analysis showed that, in detecting elevation, some listeners benefited from rotation, some benefited from natural movement, and some from both. Evidence was found indicating that a moving auditory system generates information for the whereabouts of sounds, even when the movement does not result in the listener facing the source. Results offer significant if partial support for Wallach's hypotheses.Classical theory ofauditory localization suggests that, for motionless listening, interaural cues, at least for simple sounds, provide spatial information that is essentially ambiguous. Interaural cues take the form of time differences for low-frequency acoustic energy and level differences for high-frequency energy. A classical model assumes the head to be a perfect sphere, with holes, centered on opposite sides, for ears. In this model, interaural cues specify the angle of horizontal displacement of a sound source from the median vertical plane (MVP), with the vertex of the angle at the center of the listener's head. From here on, this will be referred to as the azimuth angle. Its properties are consistent with the azimuth angle defined in the double-pole coordinate system used by Middlebrooks, Makous, and Green (1989). Figure 1 illustrates this system and shows that a particular azimuth angle encompasses a range of directions, including the direction of the source. An azimuth angle of 60°to the left, for example, specifies a cone-shaped locus covering positions forward, rearward, above, and below the interaural axisa cone ofconfusion (Woodworth & Schlosberg, 1954). It can thus be seen that, considered purely in terms ofgeometry, interaural cues alone do not specify the elevation of the source, nor whether it is forward or rearward.We wish to thank Malcolm A. Perrett, who helped provide mathematical solutions for processing of the head tracker data and whose development of the DSP software and digital signals used in the experiment formed part of his Honours (Electrical Engineering) project. Appreciation is extended to Frank Niebling for construction ofthe supporting framework for the loudspeakers and the spherical screen, and to Dean Davidson for computer programming. We also thank the reviewers of earlier drafts of the paper, whose comments led to significant developments in our thinking and practice.

Effects of head movement on front-back error in sound localization

“…It was confirmed the front-back error rate in LPN (<1 kHz) was larger than those of other stimuli as mentioned in previous studies [2][3][4][5][6][7]. A statistical test suggested that head movement may reduce the front-back error rate effectively when the duration is long.…”

“…In particular, the front-back error, in which a sound with frontal incident is wrongly perceived as coming from behind, or vice versa, may be dramatically reduced by allowing head rotation [2][3][4][5][6][7]. Perrett and Noble [4] examined the effect of the duration of sound stimuli.…”

“…In particular, the front-back error, in which a sound with frontal incident is wrongly perceived as coming from behind, or vice versa, may be dramatically reduced by allowing head rotation [2][3][4][5][6][7]. Perrett and Noble [4] examined the effect of the duration of sound stimuli. The results showed that front-back errors were significantly fewer for long stimuli (3 s) than those for short ones (0.5 s), and that front-back errors were also reduced significantly when listeners were allowed to move their heads than those in motionless condition.…”

Influence of head tracking on the externalization of speech stimuli for non-individualized binaural synthesis

“…Previous studies have shown that head movements enable subjects to localize real sources more accurately (Perrett and Noble, 1997) and reduce the number of front-back confusions (Wightman and Kistler, 1999). Head movements have been shown to be useful in distance perception of virtual sources using Wave-Field Synthesis rendering (Rébillat et al, 2012).…”

Haptic Object Localization in the Vibrissal System: Behavior and Performance

“…Fixational eye movements are important for visual processes (Kelly, 1979;Tulunay-Keesey and VerHoeve, 1987;Rucci and Desbordes, 2003), head movements may assist in sound localization (Wallach, 1940;Perret and Noble, 1997;Wightman and Kistler, 1999), and hand movements improve tactile performance (Lamb, 1983;Gamzu and Ahissar, 2001). Movements of eyes and hands move stimuli across sensory receptors, thus enriching sensation with information unavailable when stimuli are fixed in place on the eye or hand (Ahissar and Arieli, 2001).…”