Auditory Attention Essay Example for Free

Auditory Attention Essay The ability to localize sound sources is of considerable importance to both humans and animals; it will determine the direction of objects to seek or to avoid as well as indicating the appropriate direction to direct visual attention. The precision of sound localization is remarkable, particularly for brief sounds or for those occurring in noisy or reverberant surroundings. While the most reliable cues used in the localization of sounds depend upon a comparison of the signals reaching the two ears, there are also phenomena of auditory space perception which result from monoaural processing of the signals. Localization refers to judgments of the direction and distance of a sound source. Like when headphones are worn, the sound image is located inside the head. Headphones allow precise control of interaural differences and eliminate effects related to room echoes. Using two ears we are able to selectively attend to sounds coming from a particular direction while effectively excluding other sounds. This ability is particularly important in noisy surroundings or when there are several sound sources competing for our attention. Our acuity in locating sounds is greatest in the horizontal dimension, fairly good in the vertical direction and least good in the depth dimension. Aside from this ability we are also able to judge the direction of a sound source and to some extent estimates its distance. Many everyday experiences indicate that auditory localization can be influenced by conflicting visual cues. At a cinema for example, the loudspeakers are usually placed behind the screen or in its center yet the sound still appears to come from the actor’s mouth as he moves about the screen. Similarly, the loudspeaker in a television set is located to one side of the screen but the sound does not appear to be detached from the visual image. Thus, it might be possible that exposure to conflicting auditory and visual cues for a period of time may lead to an after-effect in which the localization of sounds is systematically displaced. This may occur during experiments wherein sound may be generates from one area but a cue may say otherwise and given the effects of practice and priming, experiment results into auditory localization may not be valid. Early findings on the study of orienting pure auditory attention have yielded no significant change in performance. Posner (1980) did not find any advantage in the use of auditory pre- cueing of auditory targets. Others have failed to find a benefit for the detection of sounds coming from expected vs. unexpected locations (Scharf, Quigley, Aoki, Peachey and Reeves, 1987). Buchtel and Butter (1988) found that informative auditory cues provided a benefit in the detection of visual targets; however they failed to find a benefit from cues on auditory targets. Klein, Brennan and Gilani (1987) also found no benefit in the detection of auditory targets with the use of uninformative cues using both visual and auditory cues. However, the use of auditory and visual cues together on tasks has been promising. Previous researches on multisensory instruments have found that it can optimize performance rather than using one sensory modality. Recently Duncan, Martens and Ward (1997) found evidence of restricted attentional capacity within but not between sensory modalities. They presented streams of visual and or auditory inputs containing occasional targets to be identified and recalled, for two visual or two auditory streams they found that the identification of one target produced a sustained reduction in the ability to identify a second target. In contrast, when the streams were from both modalities, there was no such reduction in the identification of the second target. The results suggest a modality-specific restriction to concurrent attention and awareness. The results of this study have important implications for the design of complex human machine interface systems. Systems should be designed to take advantage of the spatial presentation of information to the human operator to enhance the detection rate of critical information (i. e. ; warnings). This findings support Rhodes (1987) earlier work on auditory attention where he reported that auditory attention has spatial constraints. He found that time linearly increased to localize a sound as a function of distance from the point of attention; he further proposed that even for sounds, localization is shifted through logical and topographical representations. Information presented in locations where spatial attention has been allocated has both faster and more accurate response in both visual and auditory modalities (Posner, 1980, Ward, 2000, Spence driver, 1996, 1997a, 1997b). Moreover, even if there is a limited human attentional capacity the nature of spatial attention across modalities suggests that if one modality is overloaded the attentional capacity of other modalities are not adversely affected (Duncan, Martens Ward, 1997). Thus, the best way to maximize this modality-specific restriction is to present information using both the visual and auditory modalities. Flanagan, McAnally, Martin, Meehan Oldfield (1998) found evidence of the usefulness of using both modalities. In their study, they reported that visual search times were reduced when spatially informative auditory information was supplied. They used a spatial localization task in which the search for a visual target was aided by either a visual arrow or an auditory cue. They found both the visual and the auditory cues aided in significantly reducing the search times when compared to unaided search. It is however important that the visual and auditory information presented are detectable and localizable. Hence a signal should be localizable when information presented is critical (i. e. ; location of threats such as enemy fighters, missiles etc. ) and that information presented is expected in that location will improve response time and accuracy (Posner, 1980, Spence and Driver, 1996).