Different roles of similarity and predictability in auditory stream segregation

Sound sources often emit trains of discrete sounds, such as a series of footsteps. Previously, two dif¬ferent principles have been suggested for how the human auditory system binds discrete sounds to¬gether into perceptual units. The feature similarity principle is based on linking sounds with similar characteristics over time. The predictability principle is based on linking sounds that follow each other in a predictable manner. The present study compared the effects of these two principles. Participants were presented with tone sequences and instructed to continuously indicate whether they perceived a single coherent sequence or two concurrent streams of sound. We investigated the influence of separate manipulations of similarity and predictability on these perceptual reports. Both grouping principles affected perception of the tone sequences, albeit with different characteristics. In particular, results suggest that whereas predictability is only analyzed for the currently perceived sound organization, feature similarity is also analyzed for alternative groupings of sound. Moreover, changing similarity or predictability within an ongoing sound sequence led to markedly different dynamic effects. Taken together, these results provide evidence for different roles of similarity and predictability in auditory scene analysis, suggesting that forming auditory stream representations and competition between alter¬natives rely on partly different processes

Participation and quality of life in children with Duchenne muscular dystrophy using the International Classification of Functioning, Disability, and Health

<p>Abstract</p> <p>Background</p> <p>Duchenne muscular dystrophy (DMD) is characterized by muscle damage and progressive loss of muscle function in male children. DMD is one of the most devastating genetically linked neuromuscular diseases for which there is currently no cure. Most clinical studies for DMD utilize a standard protocol for measurement exploring pathophysiology, muscle strength and timed tasks. However, we propose that examining broader components of health as emphasized by the International Classification of Functioning, Disability and Health-Children and Youth Version (ICF-CY) may be of great value to children and their families, and important outcomes for future clinical trials.</p> <p>Methods</p> <p>Fifty boys with DMD and 25 unaffected age-matched boys completed two self-report measures: the Children’s Assessment of Participation and Enjoyment and the Pediatric Quality of Life Inventory^TM 4.0. We investigated differences between the two groups with regard to participation in life activities and perceived quality of life (QoL). Additionally, we compared participation in activities and QoL in both cohorts of younger and older boys.</p> <p>Results</p> <p>Participation in physical activities was significantly lower in boys with DMD than unaffected boys. Perceived QoL was markedly diminished in children with DMD relative to unaffected controls, except in the emotional domain. The amount of time boys engage in an activity, as well as participation in social activities, declined for our older boys with DMD but no changes were observed for our older unaffected boys. For both groups, QoL remained constant over time.</p> <p>Conclusions</p> <p>The ICF-CY provides a conceptual framework and specific terminology that facilitates investigation of the consequences of impairment in children and youth. Our study is one of the first to explore participation in a cohort of boys with DMD. It was not surprising that activities of choice for boys with DMD were less physical in nature than unaffected boys their age, but the consequences of less social engagement as the boys with DMD age is of great concern. Results from our study underscore the need to further evaluate activities that children elect to participate in, with special emphasis on facilitators and barriers to participation and how participation changes throughout the course of a disease.</p

The role of perceived source location in auditory stream segregation: separation affects sound organization, common fate does not

The human auditory system is capable of grouping sounds originating from different sound sources into coherent auditory streams, a process termed auditory stream segregation. Several cues can influence auditory stream segregation, but the full set of cues and the way in which they are integrated is still unknown. In the current study, we tested whether auditory motion can serve as a cue for segregating sequences of tones. Our hypothesis was that, following the principle of common fate, sounds emitted by sources moving together in space along similar trajectories will be more likely to be grouped into a single auditory stream, while sounds emitted by independently moving sources will more often be heard as two streams. Stimuli were derived from sound recordings in which the sound source motion was induced by walking humans. Although the results showed a clear effect of spatial separation, auditory motion had a negligible influence on stream segregation. Hence, auditory motion may not be used as a primitive cue in auditory stream segregation

Case Study: Monitoring Sleeping Patterns of a Boy with Duchenne Muscular Dystrophy and his Caregivers

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The effects of rhythm and melody on auditory stream segregation

Whilst many studies have assessed the efficacy of similarity-based cues for auditory stream segregation, much less is known about whether and how the larger-scale structure of sound sequences support stream formation and the choice of sound organization. Two experiments investigated the effects of musical melody and rhythm on the segregation of two interleaved tone sequences. The two sets of tones fully overlapped in pitch range, but differed from each other in interaural time and intensity. Unbeknownst to the listener, separately, each of the interleaved sequences was created from the notes of a different song. In different experimental conditions, the notes and/or their timing could either follow those of the songs, or they could be scrambled or, in case of timing, set to be isochronous. Listeners were asked to continuously report whether they heard a single coherent sequence (integrated) or two concurrent streams (segregated). Although temporal overlap between tones from the two streams proved to be the strongest cue for stream segregation, significant effects of tonality and familiarity with the songs were also observed. These results suggest that the regular temporal patterns are utilized as cues in auditory stream segregation and that long-term memory is involved in this process