Optimal Allocation of Societal HIV Prevention Resources to Reduce HIV Incidence in the United States.

Objectives. To optimize combined public and private spending on HIV prevention to achieve maximum reductions in incidence.Methods. We used a national HIV model to estimate new infections from 2018 to 2027 in the United States. We estimated current spending on HIV screening, interventions that move persons with diagnosed HIV along the HIV care continuum, pre-exposure prophylaxis, and syringe services programs. We compared the current funding allocation with 2 optimal scenarios: (1) a limited-reach scenario with expanded efforts to serve eligible persons and (2) an ideal, unlimited-reach scenario in which all eligible persons could be served.Results. A continuation of the current allocation projects 331 000 new HIV cases over the next 10 years. The limited-reach scenario reduces that number by 69%, and the unlimited reach scenario by 94%. The most efficient funding allocations resulted in prompt diagnosis and sustained viral suppression through improved screening of high-risk persons and treatment adherence support for those infected.Conclusions. Optimal allocations of public and private funds for HIV prevention can achieve substantial reductions in new infections. Achieving reductions of more than 90% under current funding will require that virtually all infected receive sustained treatment.

Vital Signs: HIV Transmission Along the Continuum of Care - United States, 2016.

BACKGROUND: In 2016, an estimated 1.1 million persons had human immunodeficiency virus (HIV) infection in the United States; 38,700 were new infections. Knowledge of HIV infection status, behavior change, and antiretroviral therapy (ART) all prevent HIV transmission. Persons who achieve and maintain viral suppression (achieved by most persons within 6 months of starting ART) can live long, healthy lives and pose effectively no risk of HIV transmission to their sexual partners. METHODS: A model was used to estimate transmission rates in 2016 along the HIV continuum of care. Data for sexual and needle-sharing behaviors were obtained from National HIV Behavioral Surveillance. Estimated HIV prevalence, incidence, receipt of care, and viral suppression were obtained from National HIV Surveillance System data. RESULTS: Overall, the HIV transmission rate was 3.5 per 100 person-years in 2016. Along the HIV continuum of care, the transmission rates from persons who were 1) acutely infected and unaware of their infection, 2) non-acutely infected and unaware, 3) aware of HIV infection but not in care, 4) receiving HIV care but not virally suppressed, and 5) taking ART and virally suppressed were 16.1, 8.4, 6.6, 6.1, and 0 per 100 person-years, respectively. The percentages of all transmissions generated by each group were 4.0%, 33.6%, 42.6%, 19.8%, and 0%, respectively. CONCLUSION: Approximately 80% of new HIV transmissions are from persons who do not know they have HIV infection or are not receiving regular care. Going forward, increasing the percentage of persons with HIV infection who have achieved viral suppression and do not transmit HIV will be critical for ending the HIV epidemic in the United States.

Selecting Evidence-Based HIV Prevention Behavioral Interventions for HIV-Negative Persons for National Dissemination.

This paper describes the development of a formula to determine which evidence-based behavioral interventions (EBIs) targeting HIV-negative persons would be cost-saving in comparison to the lifetime cost of HIV treatment and the process by which this formula was used to prioritize those with greatest potential impact for continued dissemination. We developed a prevention benefit index (PBI) to rank risk-reduction EBIs for HIV-negative persons based on their estimated cost for achieving the behavior change per one would-be incident infection of HIV. Inputs for calculating the PBI included the mean estimated cost-per-client served, EBI effect size for the behavior change, and the HIV incidence per 100,000 persons in the target population. EBIs for which the PBI was ≤ $402,000, the estimated lifetime cost of HIV care, were considered cost-saving. We were able to calculate a PBI for 35 EBI and target population combinations. Ten EBIs were cost-saving having a PBI below $402,000. One EBI did not move forward for dissemination due to high start-up dissemination costs. DHAP now supports the dissemination of 9 unique EBIs targeting 13 populations of HIV-negative persons. The application of a process, such as the PBI, may assist other health-field policymakers when making decisions about how to select and fund implementation of EBIs.

Auditory Localization and Spatial Release From Masking in Children With Suspected Auditory Processing Disorder.

OBJECTIVES: We sought to investigate whether children referred to our audiology clinic with a complaint of listening difficulty, that is, suspected of auditory processing disorder (APD), have difficulties localizing sounds in noise and whether they have reduced benefit from spatial release from masking. DESIGN: Forty-seven typically hearing children in the age range of 7 to 17 years took part in the study. Twenty-one typically developing (TD) children served as controls, and the other 26 children, referred to our audiology clinic with listening problems, were the study group: suspected APD (sAPD). The ability to localize a speech target (the word "baseball") was measured in quiet, broadband noise, and speech-babble in a hemi-anechoic chamber. Participants stood at the center of a loudspeaker array that delivered the target in a diffused noise-field created by presenting independent noise from four loudspeakers spaced 90° apart starting at 45°. In the noise conditions, the signal-to-noise ratio was varied between -12 and 0 dB in 6-dB steps by keeping the noise level constant at 66 dB SPL and varying the target level. Localization ability was indexed by two metrics, one assessing variability in lateral plane [lateral scatter (Lscat)] and the other accuracy in the front/back dimension [front/back percent correct (FBpc)]. Spatial release from masking (SRM) was measured using a modified version of the Hearing in Noise Test (HINT). In this HINT paradigm, speech targets were always presented from the loudspeaker at 0°, and a single noise source was presented either at 0°, 90°, or 270° at 65 dB A. The SRM was calculated as the difference between the 50% correct HINT speech reception threshold obtained when both speech and noise were collocated at 0° and when the noise was presented at either 90° or 270°. RESULTS: As expected, in both groups, localization in noise improved as a function of signal-to-noise ratio. Broadband noise caused significantly larger disruption in FBpc than in Lscat when compared with speech babble. There were, however, no group effects or group interactions, suggesting that the children in the sAPD group did not differ significantly from TD children in either localization metric (Lscat and FBpc). While a significant SRM was observed in both groups, there were no group effects or group interactions. Collectively, the data suggest that children in the sAPD group did not differ significantly from the TD group for either binaural measure investigated in the study. CONCLUSIONS: As is evident from a few poor performers, some children with listening difficulties may have difficulty in localizing sounds and may not benefit from spatial separation of speech and noise. However, the heterogeneity in APD and the variability in our data do not support the notion that localization is a global APD problem. Future studies that employ a case study design might provide more insights.

Factors Associated with State Variation in Mortality Among Persons Living with Diagnosed HIV Infection.

In the United States, the all-cause mortality rate among persons living with diagnosed HIV infection (PLWH) is almost twice as high as among the general population. We aimed to identify amendable factors that state public health programs can influence to reduce mortality among PLWH. Using generalized estimating equations (GEE), we estimated age-group-specific models (24-34, 35-54, ≥ 55 years) to assess the association between state-level mortality rates among PLWH during 2010-2014 (National HIV Surveillance System) and amendable factors (percentage of Ryan White HIV/AIDS Program (RWHAP) clients with viral suppression, percentage of residents with healthcare coverage, state-enacted anti-discrimination laws index) while controlling for sociodemographic nonamendable factors. Controlling for nonamendable factors, states with 5% higher viral suppression among RWHAP clients had a 3-5% lower mortality rates across all age groups [adjusted Risk Ratio (aRR): 0.95, 95% Confidence Interval (CI): 0.92-0.99 for 24-34 years, aRR: 0.97, 95%CI: 0.94-0.99 for 35-54 years, aRR: 0.96, 95%CI: 0.94-0.99 for ≥ 55 years]; states with 5% higher health care coverage had 4-11% lower mortality rate among older age groups (aRR: 0.96, 95%CI: 0.93-0.99 for 34-54 years; aRR: 0.89, 95%CI: 0.81-0.97 for ≥ 55 years); and having laws that address one additional area of anti-discrimination was associated with a 2-3% lower mortality rate among older age groups (aRR: 0.98, 95%CI: 0.95-1.00 for 34-54 years; aRR: 0.97, 95%CI: 0.94-0.99 for ≥ 55 years). The mortality rate among PLWH was lower in states with higher levels of residents with healthcare coverage, anti-discrimination laws, and viral suppression among RWHAP clients. States can influence these factors through programs and policies.

Phase-locked responses to the vowel envelope vary in scalp-recorded amplitude due to across-frequency response interactions.

Neural encoding of the envelope of sounds like vowels is essential to access temporal information useful for speech recognition. Subcortical responses to envelope periodicity of vowels can be assessed using scalp-recorded envelope following responses (EFRs); however, the amplitude of EFRs vary by vowel spectra and the causal relationship is not well understood. One cause for spectral dependency could be interactions between responses with different phases, initiated by multiple stimulus frequencies. Phase differences can arise from earlier initiation of processing high frequencies relative to low frequencies in the cochlea. This study investigated the presence of such phase interactions by measuring EFRs to two naturally spoken vowels (/ε/ and /u/), while delaying the envelope phase of the second formant band (F2+) relative to the first formant (F1) band in 45° increments. At 0° F2+ phase delay, EFRs elicited by the vowel /ε/ were lower in amplitude than the EFRs elicited by /u/. Using vector computations, we found that the lower amplitude of /ε/-EFRs was caused by linear superposition of F1- and F2+-contributions with larger F1-F2+ phase differences (166°) compared to /u/ (19°). While the variation in amplitude across F2+ phase delays could be modeled with two dominant EFR sources for both vowels, the degree of variation was dependent on F1 and F2+ EFR characteristics. Together, we demonstrate that (a) broadband sounds like vowels elicit independent responses from different stimulus frequencies that may be out-of-phase and affect scalp-based measurements, and (b) delaying higher frequency formants can maximize EFR amplitudes for some vowels.

Patterns of Racial/Ethnic Disparities and Prevalence in HIV and Syphilis Diagnoses Among Men Who Have Sex With Men, 2016: A Novel Data Visualization.

OBJECTIVES: To describe disparities in HIV infection and syphilis among gay, bisexual, and other men who have sex with men (MSM) in US states through ratio-based measures and graphical depictions of disparities. METHODS: We used state-level surveillance data of reported HIV and syphilis cases in 2015 and 2016, and estimates of MSM population sizes to estimate HIV and syphilis prevalence by race/ethnicity and rate ratios (RRs) and to visually display patterns of disparity and prevalence among US states. RESULTS: State-specific rates of new HIV diagnoses were higher for Black than for White MSM (RR range = 2.35 [Rhode Island] to 10.12 [Wisconsin]) and for Hispanic than for White MSM (RR range = 1.50 [Tennessee] to 5.78 [Pennsylvania]). Rates of syphilis diagnoses were higher for Black than for White MSM in 42 of 44 states (state RR range = 0.89 [Hawaii] to 17.11 [Alaska]). Scatterplots of HIV diagnosis rates by race showed heterogeneity in epidemic scenarios, even in states with similar ratio-based disparity measures. CONCLUSIONS: There is a widely disparate impact of HIV and syphilis among Black and Hispanic MSM compared with White MSM. Between-state variation suggests that states should tailor and focus their prevention responses to best address state data.

Swipe Right: Dating Website and App Use Among Men Who Have Sex With Men.

This study explored the frequency of dating website and app usage among MSM to understand sub-group differences in use. Web-based survey data (N = 3105) were analyzed to assess the use of dating websites and apps. More than half (55.7%) of MSM in this sample were frequent users of dating websites and apps. Two-thirds (66.7%) of frequent users had casual partners only in the past 12 months and reported a high average number of casual sexual partners in the past 12 months (Mdn = 5.0) compared to never users (Mdn = 0.0; χ 2(2) = 734.94, adj. p < .001). The most frequently used dating website or app was Grindr, with 60.2% of the sample reporting some or frequent use. Adam4Adam (23.5%), Jack'd (18.9%) and Scruff (18.7%) were also frequently used. Dating websites and apps may be effective channels to reach a diverse group of MSM with HIV prevention messages.

Quantifying the Harms and Benefits from Serosorting Among HIV-Negative Gay and Bisexual Men: A Systematic Review and Meta-analysis.

We conducted a systematic review and meta-analysis of the association between serosorting and HIV infection among HIV-negative men who have sex with men (MSM). Compared to no condomless anal sex (i.e., consistent condom use or no anal sex), serosorting was associated with increased HIV risk (RR = 1.64, 95% CI 1.37-1.96). Compared to condomless discordant anal sex, serosorting was associated with reduced HIV risk (RR = 0.46, 95% CI 0.33-0.65). Serosorting may be an important harm reduction strategy when condoms are not consistently used, but can be harmful if HIV-negative MSM who consistently use condoms shift to using serosorting as their primary prevention strategy. The protective effects of serosorting and ways in which MSM are operationalizing serosorting are becoming more complex as additional factors affecting risk are considered (e.g., durable viral load suppression, PrEP). Understanding the potential risk and benefit of serosorting continues to be important, particularly within the context of other prevention strategies.

Modulation of auditory-motor learning in response to formant perturbation as a function of delayed auditory feedback.

The interaction of language production and perception has been substantiated by empirical studies where speakers compensate their speech articulation in response to the manipulated sound of their voice heard in real-time as auditory feedback. A recent study by Max and Maffett [(2015). Neurosci. Lett. 591, 25-29] reported an absence of compensation (i.e., auditory-motor learning) for frequency-shifted formants when auditory feedback was delayed by 100 ms. In the present study, the effect of auditory feedback delay was studied when only the first formant was manipulated while delaying auditory feedback systematically. In experiment 1, a small yet significant compensation was observed even with 100 ms of auditory delay unlike the past report. This result suggests that the tolerance of feedback delay depends on different types of auditory errors being processed. In experiment 2, it was revealed that the amount of formant compensation had an inverse linear relationship with the amount of auditory delay. One of the speculated mechanisms to account for these results is that as auditory delay increases, undelayed (and unperturbed) somatosensory feedback is given more preference for accuracy control of vowel formants.

Young People and HIV: A Call to Action.

HIV is having a significant impact on young people, among whom the rate of new diagnoses is high and health disparities are more pronounced. Incidence is increasing among young gay and bisexual men, and, among Black males, the largest percentage of new infections occur among those aged between 13 and 24 years. Youths are least likely to experience the health and prevention benefits of treatment. Nearly half of young people with HIV are not diagnosed; among those diagnosed, nearly a quarter are not linked to care, and three quarters are not virally suppressed. Addressing this burden will require renewed efforts to implement effective prevention strategies across multiple sectors, including educational, social, policy, and health care systems that influence prevention knowledge, service use, and treatment options for youths.

Occlusion effect on compensatory formant production and voice amplitude in response to real-time perturbation.

The importance of auditory feedback for controlling speech articulation has been substantiated by the use of the real-time auditory perturbation paradigm. With this paradigm, speakers receive their own manipulated voice signal in real-time while they produce a simple speech segment. In response, they spontaneously compensate for the manipulation. In the case of vowel formant control, various studies have reported behavioral and neural mechanisms of how auditory feedback is processed for compensatory behavior. However, due to technical limitations such as avoiding an electromagnetic artifact or metal transducers near a scanner, some studies require foam tip insert earphones. These earphones occlude the ear canal, and may cause more energy of the unmanipulated first formant to reach the cochlea through bone conduction and thus confound the effect of formant manipulation. Moreover, amplification of lower frequencies due to occluded ear canals may influence speakers' voice amplitude. The current study examined whether using circumaural headphones and insert earphones would elicit different compensatory speech production when speakers' first formant was manipulated in real-time. The results of the current study showed that different headphones did not elicit different compensatory formant production. Voice amplitude results were varied across different vowels examined; however, voice amplitude tended to decrease with the introduction of F1 perturbation.

Assessing HIV acquisition risks among men who have sex with men in the United States of America.

Men who have sex with men (MSM) can reduce their risk of acquiring human immunodeficiency virus (HIV) by using various prevention strategies and by understanding the effectiveness of each option over the short- and long-term. Strategies examined were: circumcision; insertive anal sex only; consistent, 100% self-reported condom use; and pre-exposure prophylaxis (PrEP). PrEP efficacy was based on three levels of adherence. The cumulative HIV acquisition risk among MSM over periods of 1 year and 10 years were estimated with and without single and combinations of prevention strategies. A Bernoulli process model was used to estimate risk. In the base case with no prevention strategies, the 1-year risk of HIV acquisition among MSM was 8.8%. In contrast, the 1-year risk associated with circumcision alone was 6.9%; with insertive sex only, 5.5%; with 100% self-reported condom use, 2.7%; and with average, high, and very high PrEP adherence, 5.1%, 2.5%, and 0.7%, respectively. The 10-year risk of HIV acquisition among MSM with no prevention strategy was 60.3%. In contrast, that associated with circumcision alone was 51.1%; with insertive sex only, 43.1%; with 100% self-reported condom use, 24.0%; and with average, high, and very high PrEP adherence, 40.5%, 22.2%, and 7.2%, respectively. While MSM face substantial risk of HIV, there are now a number of prevention strategies that reduce risk. Very high adherence to PrEP alone or with other strategies appears to be the most powerful tool for HIV prevention.

From Theory to Practice: Implementation of a Resource Allocation Model in Health Departments.

OBJECTIVE: To develop a resource allocation model to optimize health departments' Centers for Disease Control and Prevention (CDC)-funded HIV prevention budgets to prevent the most new cases of HIV infection and to evaluate the model's implementation in 4 health departments. DESIGN, SETTINGS, AND PARTICIPANTS: We developed a linear programming model combined with a Bernoulli process model that allocated a fixed budget among HIV prevention interventions and risk subpopulations to maximize the number of new infections prevented. The model, which required epidemiologic, behavioral, budgetary, and programmatic data, was implemented in health departments in Philadelphia, Chicago, Alabama, and Nebraska. MAIN OUTCOME MEASURES: The optimal allocation of funds, the site-specific cost per case of HIV infection prevented rankings by intervention, and the expected number of HIV cases prevented. RESULTS: The model suggested allocating funds to HIV testing and continuum-of-care interventions in all 4 health departments. The most cost-effective intervention for all sites was HIV testing in nonclinical settings for men who have sex with men, and the least cost-effective interventions were behavioral interventions for HIV-negative persons. The pilot sites required 3 to 4 months of technical assistance to develop data inputs and generate and interpret the results. Although the sites found the model easy to use in providing quantitative evidence for allocating HIV prevention resources, they criticized the exclusion of structural interventions and the use of the model to allocate only CDC funds. CONCLUSIONS: Resource allocation models have the potential to improve the allocation of limited HIV prevention resources and can be used as a decision-making guide for state and local health departments. Using such models may require substantial staff time and technical assistance. These model results emphasize the allocation of CDC funds toward testing and continuum-of-care interventions and populations at highest risk of HIV transmission.

Syndemic vulnerability, sexual and injection risk behaviors, and HIV continuum of care outcomes in HIV-positive injection drug users.

Limited investigations have been conducted on syndemics and HIV continuum of care outcomes. Using baseline data from a multi-site, randomized controlled study of HIV-positive injection drug users (n = 1,052), we examined whether psychosocial factors co-occurred, and whether these factors were additively associated with behavioral and HIV continuum of care outcomes. Experiencing one type of psychosocial problem was significantly (p < 0.05) associated with an increased odds of experiencing another type of problem. Persons with 3 or more psychosocial problems were significantly more likely to report sexual and injection risk behaviors and were less likely to be adherent to HIV medications. Persons with 4 or more problems were less likely to be virally suppressed. Reporting any problems was associated with not currently taking HIV medications. Our findings highlight the association of syndemics not only with risk behaviors, but also with outcomes related to the continuum of care for HIV-positive persons.

Evaluation of Speech-Evoked Envelope Following Responses as an Objective Aided Outcome Measure: Effect of Stimulus Level, Bandwidth, and Amplification in Adults With Hearing Loss.

OBJECTIVES: The present study evaluated a novel test paradigm based on speech-evoked envelope following responses (EFRs) as an objective aided outcome measure for individuals fitted with hearing aids. Although intended for use in infants with hearing loss, this study evaluated the paradigm in adults with hearing loss, as a precursor to further evaluation in infants. The test stimulus was a naturally male-spoken token /susa∫i/, modified to enable recording of eight individual EFRs, two from each vowel for different formants and one from each fricative. In experiment I, sensitivity of the paradigm to changes in audibility due to varying stimulus level and use of hearing aids was tested. In experiment II, sensitivity of the paradigm to changes in aided audible bandwidth was evaluated. As well, experiment II aimed to test convergent validity of the EFR paradigm by comparing the effect of bandwidth on EFRs and behavioral outcome measures of hearing aid fitting. DESIGN: Twenty-one adult hearing aid users with mild to moderately severe sensorineural hearing loss participated in the study. To evaluate the effects of level and amplification in experiment I, the stimulus was presented at 50 and 65 dB SPL through an ER-2 insert earphone in unaided conditions and through individually verified hearing aids in aided conditions. Behavioral thresholds of EFR carriers were obtained using an ER-2 insert earphone to estimate sensation level of EFR carriers. To evaluate the effect of aided audible bandwidth in experiment II, EFRs were elicited by /susa∫i/ low-pass filtered at 1, 2, and 4 kHz and presented through the programmed hearing aid. EFRs recorded in the 65 dB SPL aided condition in experiment I represented the full bandwidth condition. EEG was recorded from the vertex to the nape of the neck over 300 sweeps. Speech discrimination using the University of Western Ontario Distinctive Feature Differences test and sound quality rating using the Multiple-Stimulus Hidden Reference and Anchor paradigm were measured in the same bandwidth conditions. RESULTS: In experiment I, an increase in stimulus level above threshold and the use of amplification resulted in a significant increase in the number of EFRs detected per condition. At positive sensation levels, an increase in level demonstrated a significant increase in response amplitude in unaided and aided conditions. At 50 and 65 dB SPL, the use of amplification led to a significant increase in response amplitude for the majority of carriers. In experiment II, the number of EFR detections and the combined response amplitude of all eight EFRs improved with an increase in bandwidth up to 4 kHz. In contrast, behavioral measures continued to improve at wider bandwidths. Further change in EFR parameters was possibly limited by the hearing aid bandwidth. Significant positive correlations were found between EFR parameters and behavioral test scores in experiment II. CONCLUSIONS: The EFR paradigm demonstrates sensitivity to changes in audibility due to a change in stimulus level, bandwidth, and use of amplification in clinically feasible test times. The paradigm may thus have potential applications as an objective aided outcome measure. Further investigations exploring stimulus-response relationships in aided conditions and validation studies in children are warranted.

Effect of Stimulus Level and Bandwidth on Speech-Evoked Envelope Following Responses in Adults With Normal Hearing.

OBJECTIVE: The use of auditory evoked potentials as an objective outcome measure in infants fitted with hearing aids has gained interest in recent years. This article proposes a test paradigm using speech-evoked envelope following responses (EFRs) for use as an objective-aided outcome measure. The method uses a running speech-like, naturally spoken stimulus token /susa∫i/ (fundamental frequency [f0] = 98 Hz; duration 2.05 sec), to elicit EFRs by eight carriers representing low, mid, and high frequencies. Each vowel elicited two EFRs simultaneously, one from the region of formant one (F1) and one from the higher formants region (F2+). The simultaneous recording of two EFRs was enabled by lowering f0 in the region of F1 alone. Fricatives were amplitude modulated to enable recording of EFRs from high-frequency spectral regions. The present study aimed to evaluate the effect of level and bandwidth on speech-evoked EFRs in adults with normal hearing. As well, the study aimed to test convergent validity of the EFR paradigm by comparing it with changes in behavioral tasks due to bandwidth. DESIGN: Single-channel electroencephalogram was recorded from the vertex to the nape of the neck over 300 sweeps in two polarities from 20 young adults with normal hearing. To evaluate the effects of level in experiment I, EFRs were recorded at test levels of 50 and 65 dB SPL. To evaluate the effects of bandwidth in experiment II, EFRs were elicited by /susa∫i/ low-pass filtered at 1, 2, and 4 kHz, presented at 65 dB SPL. The 65 dB SPL condition from experiment I represented the full bandwidth condition. EFRs were averaged across the two polarities and estimated using a Fourier analyzer. An F test was used to determine whether an EFR was detected. Speech discrimination using the University of Western Ontario Distinctive Feature Differences test and sound quality rating using the Multiple Stimulus Hidden Reference and Anchors paradigm were measured in identical bandwidth conditions. RESULTS: In experiment I, the increase in level resulted in a significant increase in response amplitudes for all eight carriers (mean increase of 14 to 50 nV) and the number of detections (mean increase of 1.4 detections). In experiment II, an increase in bandwidth resulted in a significant increase in the number of EFRs detected until the low-pass filtered 4 kHz condition and carrier-specific changes in response amplitude until the full bandwidth condition. Scores in both behavioral tasks increased with bandwidth up to the full bandwidth condition. The number of detections and composite amplitude (sum of all eight EFR amplitudes) significantly correlated with changes in behavioral test scores. CONCLUSIONS: Results suggest that the EFR paradigm is sensitive to changes in level and audible bandwidth. This may be a useful tool as an objective-aided outcome measure considering its running speech-like stimulus, representation of spectral regions important for speech understanding, level and bandwidth sensitivity, and clinically feasible test times. This paradigm requires further validation in individuals with hearing loss, with and without hearing aids.

Influence of the stimulus presentation rate on medial olivocochlear system assays.

Click evoked otoacoustic emissions (CEOAEs) are commonly used both in research and clinics to assay the medial olivocochlear system (MOC). Clicks presented at rates >50 Hz in the contralateral ear have previously been reported to evoke contralateral MOC activity. However, in typical MOC assays, clicks are presented in the ipsilateral ear in conjunction with MOC elicitor (noise) in the contralateral ear. The effect of click rates in such an arrangement is currently unknown. A forward masking paradigm was used to emulate typical MOC assays to elucidate the influence of ipsilateral click presentation rates on MOC inhibition of CEOAEs in 28 normal hearing adults. Influence of five click rates (20.83, 25, 31.25, 41.67, and 62.5 Hz) presented at 55 dB peSPL was tested. Results indicate that click rates as low as 31.25 Hz significantly enhance contralateral MOC inhibition, possibly through the activation of ipsilateral and binaural MOC neurons with potential contributions from the middle ear muscle reflex. Therefore, click rates ≤25 Hz are recommended for use in MOC assays, at least for 55 dB peSPL click level.

Formant compensation for auditory feedback with English vowels.

Past studies have shown that speakers spontaneously adjust their speech acoustics in response to their auditory feedback perturbed in real time. In the case of formant perturbation, the majority of studies have examined speaker's compensatory production using the English vowel /ɛ/ as in the word "head." Consistent behavioral observations have been reported, and there is lively discussion as to how the production system integrates auditory versus somatosensory feedback to control vowel production. However, different vowels have different oral sensation and proprioceptive information due to differences in the degree of lingual contact or jaw openness. This may in turn influence the ways in which speakers compensate for auditory feedback. The aim of the current study was to examine speakers' compensatory behavior with six English monophthongs. Specifically, the current study tested to see if "closed vowels" would show less compensatory production than "open vowels" because closed vowels' strong lingual sensation may richly specify production via somatosensory feedback. Results showed that, indeed, speakers exhibited less compensatory production with the closed vowels. Thus sensorimotor control of vowels is not fixed across all vowels; instead it exerts different influences across different vowels.