Visual facilitation of auditory localization in schoolchildren: A signal detection analysis

The role of vision in auditory distance perception

In humans, multisensory interaction is an important strategy for improving the detection of stimuli of different nature and reducing the variability of response. It is known that the presence of visual information affects the auditory perception in the horizontal plane (azimuth), but there are few researches that study the influence of vision in the auditory distance perception. In general, the data obtained from these studies are contradictory and do not completely define the way in which visual cues affect the apparent distance of a sound source. Here psychophysical experiments on auditory distance perception in humans are performed, including and excluding visual cues. The results show that the apparent distance from the source is affected by the presence of visual information and that subjects can store in their memory a representation of the environment that later improves the perception of distance.

Improved auditory spatial acuity in visually deprived ferrets

We have examined the effects on auditory spatial acuity in the horizontal plane of depriving ferrets of patterned visual cues by binocular eyelid suture in infancy or for a comparable period in adulthood. Minimum audible angles (MAAs) were measured for 500-, 100- and 40-ms broadband noise bursts at the midline and at 45 degrees to one side. A logistic regression analysis revealed no consistent difference between the midline MAAs of normal and infant lid-sutured ferrets. However, the lateral field MAAs of the infant-deprived group were significantly smaller and showed less inter-subject variability than those of normal-sighted ferrets. The animals deprived in adulthood were tested in the lateral field only, firstly 6 months after binocular eyelid suture and again after a further 10 months. For the first test, the MAAs achieved by these animals with 500- and 100-ms noise bursts were significantly smaller than the normal values and no different from those of the infant-deprived group. A significant improvement in performance at the two shortest stimulus durations (100 and 40 ms) was observed when the adult-deprived animals were re-tested. Their second-test MAAs did not differ from those of the infant-deprived group at any of the three stimulus durations used, and both groups achieved significantly better scores than the normal-sighted control animals. These results show that prolonged visual deprivation in both juvenile and adult ferrets can lead to a significant improvement in auditory spatial acuity in the lateral sound field. This is consistent with reports that congenitally blind humans can localize peripheral sounds more accurately than normal controls.

On listening where we look: the fragility of a phenomenon

The role of eye position information has been the subject of some debate in the literature on the visual facilitation of auditory localization and attention. In one particularly compelling study, Reisberg, Scheiber, and Potemken (1981) found that fixation position strongly influenced subjects' recall performance in a binaural selective-listening task. The present paper describes repeated failures to demonstrate the eye position effect under conditions similar to those of the original study, thus challenging the robustness of this oft-cited phenomenon of "listening where we look."