IDENTIFYING NEUROBEHAVIORAL MECHANISMS OF RHYTHMIC CUES FOR SPEECH-IN-NOISE PERCEPTION - PROJECT SUMMARY/ABSTRACT DIFFICULTIES WITH SPEECH-IN-NOISE (SIN) PERCEPTION ARE A COMMON AUDIOLOGIC COMPLAINT, AND YET CURRENT INTERVENTIONS SUCH AS HEARING AIDS DO NOT FULLY RESOLVE THESE PROBLEMS. SIN DIFFICULTIES ARE MORE COMMON WITH INCREASING AGE EVEN WITHOUT HEARING LOSS AND COGNITIVE DECLINE. GIVEN THE EXPECTED EXPONENTIAL GROWTH IN THE UNITED STATES' AGING POPULATION IN THE NEXT 25 YEARS, DEVELOPMENT OF INTERVENTIONS TO ADDRESS SIN DIFFICULTIES IS CRITICAL. EMERGING RESEARCH IN YOUNG ADULTS DEMONSTRATES THAT AUDITORY RHYTHMIC CUES FACILITATE SIN PERCEPTION. HOWEVER, SEVERAL QUESTIONS ON THIS PHENOMENON REMAIN UNANSWERED INCLUDING ITS UNDERLYING NEURAL MECHANISMS AND WHETHER RHYTHMIC CUING IS EQUALLY BENEFICIAL FOR OLDER LISTENERS WHO SHOW MORE NOISE EXCLUSION DEFICITS. TO ADDRESS THESE GAPS, WE PROPOSE A BASIC SCIENCE STUDY CENTERED AROUND RHYTHMIC CUEING OF SIN. OUR SPECIFIC AIMS ARE TO DETERMINE THE IMPACT OF AGING AND SALIENT STIMULUS FACTORS (PERIODICITY, NOISE LEVEL) ON RHYTHMIC CUEING FACILITATION OF SIN PROCESSING (AIM 1) AND IDENTIFY THE PRIMARY MECHANISM UNDERLYING RHYTHMIC CUEING BENEFITS IN YOUNGER VS. OLDER ADULTS (AIM 2). OUR GOALS ARE TO UNDERSTAND HOW RHYTHMIC CUES AMPLIFY SPEECH CODING IN THE BRAIN, WHETHER THEY ARE MOST USEFUL IN EASY VS. DIFFICULT LISTENING SCENARIOS, AND HOW AGING INFLUENCES BENEFIT FROM THESE CUES. WE WILL COLLECT ELECTROENCEPHALOGRAPHY (EEG) DATA DURING RHYTHMICALLY-CUED SIN PERCEPTION TASKS TO MEASURE HOW PRECEDING NON-SPEECH TEMPORAL CUES INFLUENCE SUBSEQUENT NEURAL PROCESSING OF TARGET SPEECH. WE HYPOTHESIZE RHYTHMIC CUES WILL INCREASE THE STRENGTH OF EEG ENTRAINMENT TO EXTERNAL TEMPORAL CUES AND THEREFORE LATER SPEECH RHYTHMS IN AN ATTENTION-DEPENDENT MANNER. WE FURTHER HYPOTHESIZE RHYTHMIC CUES WILL IMPROVE SIN RECOGNITION AND ITS NEURAL ENCODING FOR YOUNGER ADULTS, BUT THAT PERIODIC, METRONOME-LIKE CUES WILL IMPROVE SIN PROCESSING MORE FOR OLDER ADULTS DUE TO THE NEED FOR MORE ROBUST TEMPORAL STRUCTURE WITH AGE. RESULTS FROM THIS STUDY WILL BROADEN OUR UNDERSTANDING OF HOW RHYTHMIC CUES FUNCTION NEUROBEHAVIORALLY TO FACILITATE SPEECH AND SIN PERCEPTION IN THE AGING POPULATION AS WELL AS INFORM FUTURE CLINICAL INTERVENTIONS. THE PROPOSED RESEARCH PROGRAM CLOSELY ALIGNS WITH THE AGENCY'S STRATEGIC PLAN TO BETTER UNDERSTAND THE DYNAMICS OF AGING AS IT RELATES TO SPEECH PERCEPTION, AND TO EVENTUALLY IMPROVE HEALTH AND WELL- BEING OF OLDER ADULTS THROUGH THE FUTURE DEVELOPMENT OF EVIDENCE-BASED TREATMENTS.