Lori J. Leibold, Ph.D. - US grants

DESCRIPTION (provided by applicant): The long-term objective of this proposal is to investigate the influence of higher-level processes, such as attention, on the development of hearing. Specifically, two experiments are proposed to determine infant performance on a measure of recent interest in the adult psychoacoustic literature termed "informational masking". In contrast to "energetic" masking that results from masker energy falling within the same auditory filter as the signal, informational masking is produced by stimulus uncertainty. The mechanisms underlying informational masking are believed to be central in origin and are likely influenced by both listening experience and central maturity. Thus, determining age differences in informational masking has the potential to provide insight into the mechanisms underlying informational masking in adults. In addition, studying informational masking in infants offers an opportunity to advance our understanding of the influence of central processes on hearing during development. In Experiment 1, the influence of procedural modifications needed to study informational masking in infants will be examined. In Experiment 2, patterns of informational masking from infants and adults will be compared. The results of these experiments will inform the process of measuring and understanding informational masking in both infants and adults.

[unreadable] DESCRIPTION (provided by applicant): The long-term goal of this project is to identify the factors that contribute to the development of hearing in complex acoustic environments. The proposed experiments will characterize child-adult differences in susceptibility to interference from competing background sounds and will identify developmental effects in the ability to use spectral and temporal cues to improve hearing in noise. Recent studies have shown that children are more susceptible than adults to interference from competing sounds. Although the mechanisms that underlie this increased susceptibility are poorly understood, central auditory processes such as sound source determination and selective attention appear to play a major role. Little is currently known, however, about how and when these processes develop. The proposed work has two specific aims. Aim 1 will provide information that can be used to determine the course of development for susceptibility to interference from remote frequency background sounds. Aim 2 will focus on identifying acoustic cues that children rely on to detect target signals in the presence of noise. The results of the proposed studies will enhance our understanding of the factors that limit children's ability to hear in noisy environments. These studies could result in more successful speech and language outcomes for children with hearing loss and could lead to the development of strategies that improve the quality of the acoustic signal in the classroom. [unreadable] [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Infants and children are more vulnerable to interference from competing backgrounds sounds than adults. These development effects in auditory masking can be substantial for children with normal hearing sensitivity, but are more pronounced for children with hearing impairment. Despite the fact that infants must learn about speech and language in the presence of competing sounds, we have a limited understanding of the factors that influence children's hearing in noise, and few studies have addressed the specific challenges faced by infants and children with hearing impairment. The long-term aim of this project is to identify and explain the factors responsible for the development of hearing in complex acoustic environments that contain multiple sources of sound. The proposed experiments will characterize developmental effects in the ability to hear target tones or speech in the presence of competing background sounds and will identify acoustic-cue combinations that improve hearing in noise for both normal-hearing and hearing-impaired infants and children. Aim 1 will delineate the time course of development for remote-frequency masking from infancy to adolescence. The proposed studies will test the hypothesis that susceptibility to interference from remote-frequency background sounds decreases with increasing age. Aim 2 will investigate the extent to which infants and children benefit from the provision of robust and/or redundant auditory grouping cues in the presence of competing background sounds. These studies will test the hypothesis that infants and children benefit less than adults from sound source segregation cues when those cues are relatively sparse. Aim 3 will identify acoustic cues that improve hearing in the presence of competing background sounds for infants and children with hearing impairment. This work will test the hypothesis that hearing impairment interferes with auditory processing abilities related to the segregation and selection of target from background sounds. Experiments proposed for all three aims rely on rigorous behavioral methods using well-characterized multi-tonal and noise stimuli as well as speech perception testing in the presence of competing noise or speech maskers. The results of the proposed studies will provide much needed normative data and are expected to contribute to the formation of pediatric measures of complex auditory perception. There is also the potential these data will lead to improved strategies to optimize the delivery of auditory information for infants and children with hearing impairment. PUBLIC HEALTH RELEVANCE: The results of the proposed studies will provide valuable information about the factors that limit infants'and children's abilities to hear target sounds in noisy environments and the specific challenges faced by children with hearing impairment. This information is relevant to public health because it will provide much-needed normative data for clinical hearing measures designed to assess complex auditory skills. There is also the potential these data could lead to the development of new intervention strategies to improve the provision of auditory information for infants and children with hearing impairment.