Mitchell Sommers - US grants

Auditory suppression is a mechanism whereby strong excitation at one frequency can suppress activity at adjacent frequencies. In young adults, auditory suppression can significantly enhance the frequency resolving power of the auditory system (the ability to resolve individual components of complex signals). The purpose of the proposed pilot study is to examine auditory suppression in older adults to determine if age-related changes in suppressive mechanisms impair frequency resolution in this population. Age differences in auditory suppression will be investigated by comparing auditory filters (one index of frequency resolution) obtained with simultaneous and forward masking procedures in young and old adults. Comparisons of auditory filters measured with imultaneous and forward masking paradigms can provide an indication of the integrity of suppressive mechanisms because suppression is revealed in forward, but not in simultaneous, masking paradigms. Thus, as deficits in auditory suppression increase, auditory filters measured with simultaneous and forward masking procedures become more similar. The hypothesis under investigation in the proposed pilot study is that older adults will exhibit less of a difference between frequency selectivity measured with forward and simultaneous basking paradigms because age-related deficits in auditory suppression will reduce the benefits of suppressive mechanisms that have been observed in young adults. Evidence of age-related declines in auditory suppression could have important clinical implications because deficits in speech perception and other auditory functions resulting from impaired suppressive mechanisms would be uniikely to benefit from traditional clinical interventions such as amplification (hearing aids). The results of the proposed study will also provide important ilot data for a more extensive research proposal concerning age-related changes in psychoacoustic abilities, such s auditory suppression, that are independent of the well-established hearing loss in older adults and that can have profound effects on the perception of speech and other auditory stimuli.

The REU Site: Interdisciplinary Research on Aging at Washington University Center for Aging (WUCFA) project extends meaningful research opportunities in aging to 10 talented undergraduates for eight weeks each summer. The majority of the students' time is spent with their mentor in the laboratory setting. Researchers in the fields of anthropology, economics, computer science, civil engineering, psychology, and graphic design serve as mentors. The students work on a hands-on project during the eight-week session and present their project with their mentor during a research symposium the final week of the program. Students also participate in seminar sessions, informal discussion sessions, lab tours, and brown bag "lunch and learn" ethics in science sessions. Intellectual Merit - Most undergraduates have limited opportunities to gain information about, and experience with, current issues in aging. This REU site in aging has been designed to address this problem by providing an opportunity for extensive collaboration between an established investigator in aging and students interested in one or more aspects of the discipline. Participants increase their familiarity with the extant literature, gain general research skills, obtain experience with investigations in aging, and understand some of the ethical considerations specific to aging research. An important aspect of this project is developing an appreciation for the multidisciplinary nature of aging research in the next generation of aging investigators. Broader Impacts - This REU site has a number of broader impacts for the participants, faculty, WUCFA, and Washington University. First, the intensive collaboration between faculty and participants provides an ideal model for integrating discovery and teaching. By contributing to state-of-the-art research projects, REU participants and faculty have the opportunity to make important contributions to different fields of aging. At the same time, faculty provide intellectual and professional role models for participants and thereby encourage and support the next generation. Second, a strong emphasis is placed on recruiting underrepresented groups and individuals with limited opportunities to conduct research. With the average age of the population increasing for the foreseeable future, the ability to provide opportunities for gifted students with limited research opportunities to enter the field is essential to optimize research leading to productive and healthy aging. Moreover, attracting highly qualified individuals from underrepresented groups will serve to strengthen already strong ties between WUCFA and underserved groups within the community.

Interdisciplinary Research on Aging at Washington University was developed to extend meaningful research opportunities in aging to talented undergraduates. This proposal was developed out of the belief that, commensurate with its history of outstanding research in aging, Washington University should take a leading role in promoting and developing careers in aging for talented undergraduates by providing them an opportunity to gain access to and experience with issues in aging. The proposal calls for recruiting 10 undergraduate participants for an 8-week summer program at Washington University designed to provide research experience and instruction in a diverse set of areas related to aging. The activities will fall into three categories. First, the majority (80-85%) of the student's time will be spent with their mentor in the laboratory setting. Researchers in the fields of psychology, biology, social work, civil engineering, and graphic design will serve as mentors. The students will work on a hands-on project during the eight-week session and present their project with their mentor during a research symposium the final week of the program. Second, the remaining 15-20 % time will be spent in seminar sessions, informal discussion sessions, lab tours, and brown bag "lunch and learn" ethics in science sessions. Third, the students will have the opportunity to participate together in social outings outside of the training program, including a St. Louis Cardinal's ballgame, a botanical garden tour, and an overnight retreat.

Intellectual Merit. Most undergraduates have limited opportunities to gain information about, and experience with, current issues in aging. The proposed REU site in aging has been designed to address this problem by providing an opportunity for extensive collaboration between an established investigator in aging and students interested in one or more aspects of the discipline. We have developed the program to be multifaceted so that participants will increase their familiarity with the extant literature, gain general research skills, obtain experience with investigations in aging, and understand some of the ethical considerations specific to aging research. An important aspect of this application is developing an appreciation for the multidisciplinary nature of aging research in the next generation of aging investigators. We also view the establishment of an REU site administered through the Center for Aging as an opportunity to complement many of the ongoing activities in WUCFA. For example, an undergraduate research program in aging will encourage even greater interaction among WUCFA faculty and has the potential to facilitate collaboration in developing new research projects related to aging.

Broader Impacts. The proposed REU site will have a number of broader impacts for the participants, faculty, WUCFA, and Washington University. First, the intensive collaboration between faculty and participants provides an ideal model for integrating discovery and teaching. By contributing to state-of-the-art research projects, REU participants and faculty will have the opportunity to make important contributions to different fields of aging. At the same time, faculty will provide intellectual and professional role models for participants and thereby encourage and support the next generation of researchers in aging. In this regard, an important aspect of the current proposal is the fostering of long-term relationships between mentors and participants. We have therefore included a number of components, such as a provision to provide support for participants to attend conferences and a long-term follow-up plan, as critical elements in maintaining strong professional relationships between mentors and participants.

Second, a strong emphasis will be placed on recruiting underrepresented groups and individuals with limited opportunities to conduct research. Thus, the proposed REU site will attract highly capable minority students and other individuals who would not typically have an opportunity to enter the field of aging. With the average age of the population increasing for the foreseeable future, the ability to provide opportunities for gifted students with limited research opportunities to enter the field is essential to optimize research leading to productive and healthy aging. Moreover, attracting highly qualified individuals from underrepresented groups will serve to strengthen already strong ties between WUCFA and underserved groups within the community.

Last Modified Date: 05/02/09 Last Modified By: Tatiana D. Korelsky

Abstract
This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

Despite large acoustic differences in the speech of various talkers, humans are generally able to understand each other quickly and easily. The mechanisms by which humans map such variability onto a set of phonemes has been the subject of research for more than 50 years. This "speaker normalization" problem has generally been thought of in terms of normalizing the formant frequencies of a particular speaker with a reference set of formants. In this project, a novel approach to speaker normalization is explored, in which not formants but subglottal resonances
(SGRs) are normalized. SGRs have previously been shown to define a set of frequency bands within which formants may vary, yet retaining the same phonemic vowel quality. Normalizing SGRs (and associated frequency bands) therefore reduces formant variability in an effective way. In this project, effects of SGR normalization on automatic speech recognition
(ASR) performance are evaluated for both adult and child speakers of English and Spanish. In parallel, effects on human speech perception in multi-talker conditions are explored. Results are expected to improve ASR performance and shed light on human speech production and perception. The project will result in speech databases (including direct recordings of SGR acoustics) and ASR tools, which are critically useful for research in speech production, perception, speaker identification, and speech processing algorithms for cochlear implants and multi-lingual ASR. The collaboration in Engineering, Linguistics, Speech & Hearing, and Psychology facilitates a multidisciplinary learning environment.
Publications, results, databases, and tools will be disseminated to the research community.

DESCRIPTION (provided by applicant): You are not really listening to me, what I said was... For older adults, exchanges of this sort are all too familiar. Is the problem one that primarily reflects age-related impairments in sensory abilities or, instead, is it more cognitive in nature, reflecting a failure to carefully listen? Accurate speech perception requires listeners to evaluate a number of different sources of information about the content of spoken communications, including the speech signal and semantic context. In some instances, these different sources of information converge on the same perception, whereas in others they can lead to dramatically different perceptual responses. For example, an individual speaking to a nurse at a physician's office who is relying primarily on context-driven information might misperceive the sentence The Doctor said to remind you to take the BILL as The Doctor said to remind you to take the PILL. In our initial work in this area (Rogers, Jacoby, and Sommers, 2012), we have coined the term false hearing to refer to perceptual errors in which individuals rely more on context-driven than sensory-driven information, yet are nevertheless highly confident that they actually heard the stimulus. The proposed research will investigate how older and younger adults weigh sensory information and semantic context during online speech perception. In addition, we will establish the extent to which errors such as the Bill-Pill mistake reflect metacognitive failures that also produce analogous errors in other perceptual and cognitive domains. The application is highly innovative in that it integrates principles of cognition, metacognition and audiology to examine how age-related reductions in cognitive control may impair older adults' ability to flexibly vary their bases of responding. Specifically, we propose that, under conditions of equivalent intelligibility, older adults will weigh semantic context more heavily than the sensory signal as a basis for responding and will be less flexible than young listeners in switching to sensory- based responding when dictated by the prevailing circumstances. Three specific aims will be addressed in the application. Specific Aim 1 will establish how age-related changes in metacognitive abilities affect listeners' awareness of their speech perception difficulties using more naturalistic (sentence) stimuli than has been used previously. Specific aim 2 will examine how individual and age differences in cognitive control might alter communicative behaviors, such as requesting repetitions and careful listening, that could substantially improve speech perception in older adults. Specific Aim 3 will assess correlations between measures of false hearing, false seeing and false remembering to establish the extent to which these types of errors may be attributable to a common mechanism, such as cognitive control. Taken together, the findings will provide the first studies of how metacognitive abilities operate during online speech perception and whether age-related declines in metacognition contribute to the poorer speech perception performance of older adults. PUBLIC HEALTH RELEVANCE: As individuals age, there is a gradual and progressive loss of hearing. Striking results from our laboratory suggest, however, that there are many instances in which older adults are unaware of how this hearing loss affects their ability to understand speech. In the current application, we examine how failures to recognize speech perception deficits affects behaviors such as asking for repetitions, responding without understanding, and obtaining hearing aids, that can dramatically affect how well older adults are able to communicate using spoken language.