A common complaint among listeners with hearing loss (HL) is that they have difficulty communicating in common social settings. This article reviews how normal-hearing listeners cope in such settings, especially how they focus attention on a source of interest. Results of experiments with normal-hearing listeners suggest that the ability to selectively attend depends on the ability to analyze the acoustic scene and to form perceptual auditory objects properly. Unfortunately, sound features important for auditory object formation may not be robustly encoded in the auditory periphery of HL listeners. In turn, impaired auditory object formation may interfere with the ability to filter out competing sound sources. Peripheral degradations are also likely to reduce the salience of higher-order auditory cues such as location, pitch, and timbre, which enable normal-hearing listeners to select a desired sound source out of a sound mixture. Degraded peripheral processing is also likely to increase the time required to form auditory objects and focus selective attention so that listeners with HL lose the ability to switch attention rapidly (a skill that is particularly important when trying to participate in a lively conversation). Finally, peripheral deficits may interfere with strategies that normal-hearing listeners employ in complex acoustic settings, including the use of memory to fill in bits of the conversation that are missed. Thus, peripheral hearing deficits are likely to cause a number of interrelated problems that challenge the ability of HL listeners to communicate in social settings requiring selective attention.

Identification of target speech was studied under masked conditions consisting of two or four independent speech maskers. In the reference conditions, the maskers were colocated with the target, the masker talkers were the same sex as the target, and the masker speech was intelligible. The comparison conditions, intended to provide release from masking, included different-sex target and masker talkers, time-reversal of the masker speech, and spatial separation of the maskers from the target. Significant release from masking was found for all comparison conditions. To determine whether these reductions in masking could be attributed to differences in energetic masking, ideal time-frequency segregation (ITFS) processing was applied so that the time-frequency units where the masker energy dominated the target energy were removed. The remaining target-dominated “glimpses” were reassembled as the stimulus. Speech reception thresholds measured using these resynthesized ITFS-processed stimuli were the same for the reference and comparison conditions supporting the conclusion that the amount of energetic masking across conditions was the same. These results indicated that the large release from masking found under all comparison conditions was due primarily to a reduction in informational masking. Furthermore, the large individual differences observed generally were correlated across the three masking release conditions.

In complex scenes, the identity of an auditory object can build up across seconds. Given that attention operates on perceptual objects, this perceptual buildup may alter the efficacy of selective auditory attention over time. Here, we measured identification of a sequence of spoken target digits presented with distracter digits from other directions to investigate the dynamics of selective attention. Performance was better when the target location was fixed rather than changing between digits, even when listeners were cued as much as 1 s in advance about the position of each subsequent digit. Spatial continuity not only avoided well known costs associated with switching the focus of spatial attention, but also produced refinements in the spatial selectivity of attention across time. Continuity of target voice further enhanced this buildup of selective attention. Results suggest that when attention is sustained on one auditory object within a complex scene, attentional selectivity improves over time. Similar effects may come into play when attention is sustained on an object in a complex visual scene, especially in cases where visual object formation requires sustained attention.source segregation ͉ auditory scene analysis ͉ spatial hearing ͉ streaming ͉ auditory mixture I n everyday situations, we are confronted with multiple objects that compete for our attention. Both stimulus-driven and goal-related mechanisms mediate the between-object competition to determine what will be brought to the perceptual foreground (1, 2). In natural scenes, objects come and go and the object of interest can change from moment to moment, such as when the flow of conversation shifts from one talker to another at a party. Thus, our ability to analyze objects in everyday settings is directly affected by how switching attention between objects affects perception. Much of what we know about the effects of switching attention comes from visual experiments in which observers monitor rapid sequences of images or search for an item in a static field of objects (3, 4). Although these situations give insight into the time it takes to dis-and reengage attention from one object to the next, they do not directly explore whether there are dynamic effects of sustaining attention on one object through time.In contrast to visual objects, the identity of an auditory object is intimately linked to how the content of a sound evolves over time. Moreover, the process of forming an auditory object is known to evolve over seconds (5)(6)(7)(8). Given that attention is object-based (9, 10), this refinement in object formation may directly impact the selectivity of attention in a complex auditory scene. Specifically, sustaining attention on one object in a complex scene may yield more refined selectivity to the attended object over time. In turn, switching attention to a new object may reset object formation and therefore reset attentional selectivity. If so, the cost of switching attention between objects may not only be related to the time required to dis-...

Are musicians better able to understand speech in noise than non-musicians? Recent findings have produced contradictory results. Here we addressed this question by asking musicians and non-musicians to understand target sentences masked by other sentences presented from different spatial locations, the classical ‘cocktail party problem’ in speech science. We found that musicians obtained a substantial benefit in this situation, with thresholds ~6 dB better than non-musicians. Large individual differences in performance were noted particularly for the non-musically trained group. Furthermore, in different conditions we manipulated the spatial location and intelligibility of the masking sentences, thus changing the amount of ‘informational masking’ (IM) while keeping the amount of ‘energetic masking’ (EM) relatively constant. When the maskers were unintelligible and spatially separated from the target (low in IM), musicians and non-musicians performed comparably. These results suggest that the characteristics of speech maskers and the amount of IM can influence the magnitude of the differences found between musicians and non-musicians in multiple-talker “cocktail party” environments. Furthermore, considering the task in terms of the EM-IM distinction provides a conceptual framework for future behavioral and neuroscientific studies which explore the underlying sensory and cognitive mechanisms contributing to enhanced “speech-in-noise” perception by musicians.

In a variation on a procedure originally developed by Broadbent ͓͑1952͒. "Failures of attention in selective listening," J. Exp. Psychol. 44, 428-433͔ listeners were presented with two sentences spoken in a sequential, interleaved-word format. Sentence one ͑target͒ comprised the odd-numbered words in the sequence and sentence two ͑masker͒ comprised the even-numbered words in the sequence. The task was to report the words in sentence one. The goal was to determine the effectiveness of cues linking the words of the target ͑or masker͒ over time. Three such "linkage variables" were examined: ͑1͒ fixed talker, ͑2͒ fixed perceived interaural location, and ͑3͒ correct syntactic structure. All of the linkage variables provided a significant advantage when applied to the target compared to the baseline condition in which the linkage variables were randomized. However, these linkage variables were not effective when applied to the masker. Word position effects were found such that performance in the baseline condition declined, and the advantages of the linkage variables increased, for the words near the end of the sentence. Overall, this approach appears to be useful for examining interference in speech recognition that has little or no peripheral component. The results suggest that variables that link target words together improve their resiliency to interference and/or their recall.