Spoken language processing in noisy environments, a hallmark of the human brain, is subject to agerelated decline, even when peripheral hearing might be intact. The present study examines the cortical cerebral hemodynamics (measured by fMRI) associated with such processing in the aging brain. Younger and older subjects identified single words in quiet and in two multi-talker babble noise conditions (SNR 20 and −5 dB). Behaviorally, older and younger subjects did not show significant differences in the first two conditions but older adults performed less accurately in the SNR -5 condition. The fMRI results showed reduced activation in the auditory cortex but an increase in working memory and attention-related cortical areas (prefrontal and precuneus regions) in older subjects, especially in the SNR -5 condition. Increased cortical activities in general cognitive regions were positively correlated with behavioral performance in older listeners, suggestive of a compensatory strategy. Furthermore, inter-regional correlation revealed that while younger subjects showed a more streamlined cortical network of auditory regions in response to spoken word processing in noise, older subjects showed a more diffused network involving frontal and ventral brain regions. These results are consistent with the decline-compensation hypothesis, suggestive of its applicability to the auditory domain.

Objectives The purpose of this study was to obtain behavioral hearing thresholds for frequencies between 0.125 and 20 kHz from a large population between 10 and 65 years old using a clinically feasible calibration method expected to compensate well for variations in the distance between the eardrum and an insert-type sound source. Previous reports of hearing thresholds in the extended high frequencies (> 8 kHz) have either used calibration techniques known to be inaccurate or specialized equipment not suitable for clinical use. Design Hearing thresholds were measured from 352 human subjects between 10 to 65 years old having clinically normal hearing thresholds (< 20 dB HL) up to 4 kHz. An otoacoustic emission probe fitted with custom sound sources was used and the stimulus levels individually tailored based on an estimate of the insertion depth of the measurement probe. The calibrated stimulus levels were determined based on measurements made at various depths of insertion in a standard ear simulator. Threshold values were obtained for 21 frequencies between 0.125 and 20 kHz using a modified Békésy technique. Forty six of the subjects returned for a second measurement months later from the initial evaluation. Results In agreement with previous reports hearing thresholds at extended high frequencies were found to be sensitive to age related changes in auditory function. In contrast with previous reports, no gender differences were found in average hearing thresholds at most evaluated frequencies. Two aging processes, one faster than the other in time scale, appear to influence hearing thresholds in different frequency ranges. The standard deviation of test-retest threshold difference for all evaluated frequencies was 5~10 dB, comparable to that reported in the literature for similar measurement techniques, but smaller than that observed for data obtained using the standard clinical procedure. Conclusions The depth-compensated ear-simulator-based calibration method and the modified Békésy technique allow reliable measurement of hearing thresholds over the entire frequency range of human hearing. Hearing thresholds at the extended high frequencies are sensitive to aging and reveal subtle differences, which are not evident in the frequency range evaluated regularly (8 kHz and below). Previously-reported gender-related differences in hearing thresholds may be related to ear canal acoustics and the calibration procedure and not due to differences in hearing sensitivity.

Activation of medial olivocochlear efferents through contralateral acoustic stimulation ͑CAS͒ has been shown to modulate distortion product otoacoustic emission ͑DPOAE͒ level in various ways ͑enhancement, reduction, or no change͒. The goal of this study was to investigate the effect of a range of CAS levels on DPOAE fine structure. The 2f 1 -f 2 DPOAE was recorded ͑f 2 / f 1 = 1.22, L 1 = 55 dB, and L 2 =40 dB͒ from eight normal-hearing subjects, using both a frequency-sweep paradigm and a fixed frequency paradigm. Contamination due to the middle ear muscle reflex was avoided by monitoring the magnitude and phase of a probe in the test ear and by monitoring DPOAE stimulus levels throughout testing. Results show modulations in both level and frequency of DPOAE fine structure patterns. Frequency shifts observed at DPOAE level minima could explain reports of enhancement in DPOAE level due to efferent activation. CAS affected the magnitude and phase of the DPOAE component from the characteristic frequency region to a greater extent than the component from the overlap region between the stimulus tones. This differential effect explains the occasional enhancement observed in DPOAE level as well as the frequency shift in fine structure patterns.

Objective-Otoacoustic emissions and the speech-evoked auditory brainstem response are objective indices of peripheral auditory physiology and are used clinically for assessing hearing function. While each measure has been extensively explored, their interdependence and the relationships between them remain relatively unexplored.Methods-Distortion product otoacoustic emissions (DPOAE) and speech-evoked auditory brainstem responses (sABR) were recorded from 28 normal-hearing adults. Through correlational analyses, DPOAE characteristics were compared to measures of sABR timing and frequency encoding. Data were organized into two DPOAE (Strength and Structure) and five brainstem (Onset, Spectrotemporal, Harmonics, Envelope Boundary, Pitch) composite measures. Results-DPOAE Strength shows significant relationships with sABR Spectrotemporal andHarmonics measures. DPOAE Structure shows significant relationships with sABR Envelope Boundary. Neither DPOAE Strength nor Structure is related to sABR Pitch. Conclusions-The results of the present study show that certain aspects of the speech-evoked auditory brainstem responses are related to, or covary with, cochlear function as measured by distortion product otoacoustic emissions.Significance-These results form a foundation for future work in clinical populations. Analyzing cochlear and brainstem function in parallel in different clinical populations will provide a more sensitive clinical battery for identifying the locus of different disorders (e.g., language based learning impairments, hearing impairment).

BackgroundHuman immunodeficiency virus (HIV) infections are increasing among young men who have sex with men (YMSM), yet few HIV prevention programs have studied this population. Keep It Up! (KIU!), an online HIV prevention program tailored to diverse YMSM, was developed to fill this gap. The KIU! 2.0 randomized controlled trial (RCT) was launched to establish intervention efficacy.ObjectiveThe objective of the KIU! study is to advance scientific knowledge of technology-based behavioral HIV prevention, as well as improve public health by establishing the efficacy of an innovative electronic health (eHealth) prevention program for ethnically and racially diverse YMSM. The intervention is initiated upon receipt of a negative HIV test result, based on the theory that testing negative is a teachable moment for future prevention behaviors.MethodsThis is a two-group, active-control RCT of the online KIU! intervention. The intervention condition includes modules that use videos, animation, games, and interactive exercises to address HIV knowledge, motivation for safer behaviors, self-efficacy, and behavioral skills. The control condition reflects HIV information that is readily available on many websites, with the aim to understand how the KIU! intervention improves upon information that is currently available online. Follow-up assessments are administered at 3, 6, and 12 months for each arm. Testing for urethral and rectal sexually transmitted infections (STIs) is completed at baseline and at 12-month follow-up for all participants, and at 3- and 6-month follow-ups for participants who test positive at baseline. The primary behavioral outcome is unprotected anal sex at all follow-up points, and the primary biomedical outcome is incident STIs at 12-month follow-up.ResultsConsistent with study aims, the KIU! technology has been successfully integrated into a widely-used health technology platform. Baseline enrollment for the RCT was completed on December 30, 2015 (N=901), and assessment of intervention outcomes is ongoing at 3-, 6-, and 12-month time points. Upon collection of all data, and after the efficacy of the intervention has been evaluated, we will explore whether the KIU! intervention has differential efficacy across subgroups of YMSM based on ethnicity/race and relationship status.ConclusionsOur approach is innovative in linking an eHealth solution to HIV and STI home testing, as well as serving as a model for integrating scalable behavioral prevention into other biomedical prevention strategies.Trial RegistrationClinicaltrials.gov NCT01836445; https://clinicaltrials.gov/ct2/show/NCT01836445 (Archived by WebCite at http://www.webcitation.org/6myMFlxnC)

The present study examines the cerebral hemodynamics (measured by fMRI) associated with listening to speech in noise in elderly listeners with relatively normal peripheral hearing. We asked subjects to identify single words in quiet and in two multi-talker babble noise conditions (+20 and -5 dB SNRs). The behavioral results indicated that subjects performed similarly between the Quiet and +20 SNR conditions, both in accuracy and reaction time, but were less accurate and responded slower in the -5 SNR condition. There were performance-independent and SNR-dependent effects in the brain. A contrast of the +20 SNR and Quiet conditions revealed bilateral (especially left) auditory and prefrontal activation in noise despite equal behavioral performance (performance-independent but noise-dependent activations). As noise increased and behavioral performance decreased (as in the -5 SNR condition), activation in these regions increased. These results reveal a cortical network involving acoustic analysis, working memory, and auditory attention associated with speech perception in noise by the elderly. [Work supported by NIH.]