Informational factors in identifying environmental sounds in natural auditory scenes.

In a non-linguistic analog of the "cocktail-party" scenario, informational and contextual factors were found to affect the recognition of everyday environmental sounds embedded in naturalistic auditory scenes. Short environmental sound targets were presented in a dichotic background scene composed of either a single stereo background scene or a composite background scene created by playing different background scenes to the different ears. The side of presentation, time of onset, and number of target sounds were varied across trials to increase the uncertainty for the participant. Half the sounds were contextually congruent with the background sound (i.e., consistent with the meaningful real-world sound environment represented in the auditory scene) and half were incongruent. The presence of a single competing background scene decreased identification accuracy, suggesting an informational masking effect. In tandem, there was a contextual pop-out effect, with contextually incongruent sounds identified more accurately. However, when targets were incongruent with the real-world context of the background scene, informational masking was reduced. Acoustic analyses suggested that this contextual pop-out effect was driven by a mixture of perceptual differences between the target and background, as well as by higher-level cognitive factors. These findings indicate that identification of environmental sounds in naturalistic backgrounds is an active process that requires integrating perceptual, attentional, and cognitive resources.