Perception Of Auditory Cues Research Articles

Sensitivity to binaural cues beyond threshold as revealed by eye movements

Binaural cues are paramount for sound localization along the azimuth. Studies on the perception of the critical binaural cues, interaural time and level differences (ITDs and ILDs, respectively), typically measure sensitivity at threshold using N-interval, forced choice paradigms. This approach gives little or no information regarding perceptual abilities beyond threshold. In this study, an anticipatory eye movement (AEM) paradigm (cf. McMurray, 2004) was used as a novel measure to study binaural cue sensitivity throughout a wide perceptual range. This paradigm is sensitive to gradient (rather than all-or-none) perception of auditory cues. Adults with normal hearing visually tracked the location of a ball that becomes hidden on a computer screen, and anticipated its motion and reappearance via eye movements guided by binaural cues. The auditory stimuli were 4.8-s 1/3-octave narrowband noises centered at different frequencies, and contained an ILD or ITD change, indicating the impending motion of the ball. Greater cue levels elicited systematically quicker and more accurate saccades. ILD-driven AEMs were elicited for all noise center frequencies, with greater sensitivity for higher frequency noises, consistent with ecological significance. Eye movements in this study suggest variation in binaural cue perception beyond threshold that is gradient in terms of latency and accuracy.

Short-term visual deprivation improves the perception of harmonicity.

Neuroimaging studies have shown that the perception of auditory stimuli involves occipital cortical regions traditionally associated with visual processing, even in the absence of any overt visual component to the task. Analogous behavioral evidence of an interaction between visual and auditory processing during purely auditory tasks comes from studies of short-term visual deprivation on the perception of auditory cues, however, the results of such studies remain equivocal. Although some data have suggested that visual deprivation significantly increases loudness and pitch discrimination and reduces spatial localization inaccuracies, it is still unclear whether such improvement extends to the perception of spectrally complex cues, such as those involved in speech and music perception. We present data demonstrating that a 90-min period of visual deprivation causes a transient improvement in the perception of harmonicity: a spectrally complex cue that plays a key role in music and speech perception. The results provide clear behavioral evidence supporting a role for the visual system in the processing of complex auditory stimuli, even in the absence of any visual component to the task.

Perceptual effects in auralization of virtual rooms

By using various types of binaural simulation (or ‘‘auralization’’) of physical environments, it is now possible to study basic perceptual issues relevant to room acoustics, as well to simulate the acoustic conditions found in concert halls and other auditoria. Binaural simulation of physical spaces in general is also important to virtual reality systems. This presentation will begin with an overview of the issues encountered in the auralization of room and other environments. We will then discuss the influence of various approximations in room modeling, in particular, edge- and surface scattering, on the perceived room response. Finally, we will discuss cross-modal effects, such as the influence of visual cues on the perception of auditory cues, and the influence of cross-modal effects on the judgement of ‘‘perceived presence’’ and the rating of room acoustic quality.