Maximum Output and Low-Frequency Limitations of B71 and B81 Clinical Bone Vibrators: Implications for Vestibular Evoked Potentials Objectives: Bone-conducted vestibular evoked myogenic potentials (VEMPs) are tuned to have their maximum amplitude in response to tone bursts at or below 250 Hz. The low-frequency limitations of clinical bone vibrators have not been established for transient, tone burst stimuli at frequencies that are optimal for eliciting VEMPs. Design: Tone bursts with frequencies of 250 to 2000 Hz were delivered to B71 and B81 bone vibrators and their output was examined using an artificial mastoid. The lower-frequency limit of the transducers was evaluated by examining the spectral output of the bone vibrators. Maximum output levels were evaluated by measuring input–output functions across a range of stimulus levels. Results: Both the B71 and B81 could produce transient tone bursts with frequency as low as 400 Hz. However, tone bursts with frequencies of 250 and 315 Hz resulted in output with peak spectral energy at approximately 400 Hz. From 500 to 2000 Hz, maximum output levels within the linear range were between 120 and 128 dB peak force level. The newer B81 bone vibrator had a maximum output approximately 5 dB higher than the B71 at several frequencies. Conclusions: These findings demonstrate that both transducers can reach levels appropriate to elicit bone-conducted VEMPs, but the low-frequency limitations of these clinical bone vibrators limit tone burst frequency to approximately 400 Hz when attempting to stimulate the otolith organs via tone bursts. ACKNOWLEDGMENTS: Portions of the data reported here partially fulfilled requirements for an AuD class (A.A., V.B., M.C., E.S., A.T., and V.W.). Funding for this research was provided, in part, by research grants from the James Madison University College of Health and Behavioral Studies (C.G.C. and E.G.P.) and from the James Madison University Provost’s Office (C.G.C. and E.G.P.). All authors designed and performed the research. All authors analyzed the data. C.G.C. and E.G.P. wrote the paper. The authors have no conflicts of interest to disclose. Received May 15, 2019; accepted August 8, 2019. Address for correspondence: Christopher G. Clinard, Department of Communication Sciences and Disorders, James Madison University, 235 MLK Jr. Way, MSC 4304, HBS 1024, Harrisonburg, VA 22807, USA. E-mail: clinarcg@jmu.edu Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

Auditory Training Supports Auditory Rehabilitation: A State-of-the-Art Review Objectives: Auditory training (AT), which is active listening to various auditory stimuli, aims to improve auditory skills. There is evidence that AT can be used as a tool in auditory rehabilitation to improve speech perception and other auditory cognitive skills in individuals with hearing impairment. The present state-of-the-art review examines the effect of AT on communication abilities in individuals with hearing impairment. In particular, transfer of AT effects on performance in untrained speech perception tasks was evaluated. Design: PubMed, Medline, and Web of Science databases were searched using combinations of key words with restriction to the publication date from December 2012 until December 2018. The participant, intervention, control, outcome, and study design criteria were used for the inclusion of articles. Only studies comparing effects in an intervention group to a control group were considered. The target group included individuals with a mild to moderately severe hearing impairment, with and without hearing-aid experience. Out of 265 article abstracts reviewed, 16 met the predefined criteria and were taken for review. Results: The majority of studies that were included in this state of- the-art review report at least one outcome measure that shows an improvement in non-trained tasks after a period of intense AT. However, observed shortcomings are that a comparison between studies remains difficult as training benefits were assessed with various outcome measures. Also, the sustainability of training benefits was not investigated sufficiently. Conclusions: Recent evidence suggests that intensive auditory (-cognitive) training protocols are a valid tool to improve auditory communication skills. Individuals with hearing impairment seem to benefit the most using a combination of sensory rehabilitation with hearing aids and AT to enhance auditory rehabilitation. Long term benefits of AT are still not consistently observed and should be in the focus of future research. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and text of this article on the journal's Web site (www.ear-hearing.com). ACKNOWLEDGMENTS: We thank Jena Anne Schnittker for proof-reading the manuscript. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. M.S., J.B., and S.L. were responsible for conception and design of the project. M.S. conducted the literature research, article screening, data extraction, and wrote the manuscript. J.B. supported the article screening, provided expert review on the analysis, and added valuable content to the manuscript. S.L. added important intellectual content to the project and critically reviewed the manuscript. The authors have no conflicts of interest to disclose. Received December 14, 2018; accepted August 16, 2019. Address for correspondence: Maren Stropahl, Department of Science and Technology, Sonova AG, Laubisruetistrasse 28, 8712 Staefa, Switzerland. E-mail: maren.stropahl@sonova.com This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

Interaction Between Electric and Acoustic Stimulation Influences Speech Perception in Ipsilateral EAS Users Objectives: The aim of this study was to determine electric-acoustic masking in cochlear implant users with ipsilateral residual hearing and different electrode insertion depths and to investigate the influence on speech reception. The effects of different fitting strategies—meet, overlap, and a newly developed masking adjusted fitting (UNMASKfit)—on speech reception are compared. If electric-acoustic masking has a detrimental effect on speech reception, the individualized UNMASKfit map might be able to reduce masking and thereby enhance speech reception. Design: Fifteen experienced MED-EL Flex electrode recipients with ipsilateral residual hearing participated in a crosssover design study using three fitting strategies for 4 weeks each. The following strategies were compared: (1) a meet fitting, dividing the frequency range between electric and acoustic stimulation, (2) an overlap fitting, delivering part of the frequency range both acoustically and electrically, and (3) the UNMASKfit, reducing the electric stimulation according to the individual electric-on-acoustic masking strength. A psychoacoustic masking procedure was used to measure the changes in acoustic thresholds due to the presence of electric maskers. Speech reception was measured in noise with the Oldenburg Matrix Sentence test. Results: Behavioral thresholds of acoustic probe tones were significantly elevated in the presence of electric maskers. A maximum of masking was observed when the difference in location between the electric and acoustic stimulation was around one octave in place frequency. Speech reception scores and strength of masking showed a dependency on residual hearing, and speech reception was significantly reduced in the overlap fitting strategy. Electric- acoustic stimulation significantly improved speech reception over electric stimulation alone, with a tendency toward a larger benefit with the UNMASKfit map. In addition, masking was significantly inversely correlated to the speech reception performance difference between the overlap and the meet fitting. Conclusions: (1) This study confirmed the interaction between ipsilateral electric and acoustic stimulation in a psychoacoustic masking experiment. (2) The overlap fitting yielded poorer speech reception performance in stationary noise especially in subjects with strong masking. (3) The newly developed UNMASKfit strategy yielded similar speech reception thresholds with an enhanced acoustic benefit, while at the same time reducing the electric stimulation. This could be beneficial in the long-term if applied as a standard fitting, as hair cells are exposed to less possibly adverse electric stimulation. In this study, the UNMASKfit allowed the participants a better use of their natural hearing even after 1 month of adaptation. It might be feasible to transfer these results to the clinic, by fitting patients with the UNMASKfit upon their first fitting appointment, so that longer adaptation times can further improve speech reception. ACKNOWLEDGMENTS: The authors thank the subjects who dedicated their time and effort to this study. W.N. and M.I. received funding for this research from the DFG (German Research Foundation) Cluster of Excellence EXC 1077/1 ‘Hearing4all,' the DFG project Number 396932747 and MED-EL Medical Electronics. M.I. designed and performed experiments, co-designed the fitting rule, analyzed data and wrote the article. W.N. designed the experiments, co-designed the fitting rule, provided analysis, and contributed to the writing of the article. B.K. designed the experiments, provided analysis, and critical revision of the manuscript. T.L. and A.B. provided critical revision for experimental design and manuscript. The remaining authors have no conflicts of interest to disclose. Received March 12, 2019; accepted August 30, 2019. Address for correspondence: Marina Imsiecke, Deutsches HörZentrum Hannover, Department of Otorhinolaryngology, Karl-Wiechert-Allee 3, 30625 Hannover, Germany. E-mail: imsiecke.marina@mh-hannover.de This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

Detection and Attention for Auditory, Visual, and Audiovisual Speech in Children with Hearing Loss Objectives: Efficient multisensory speech detection is critical for children who must quickly detect/encode a rapid stream of speech to participate in conversations and have access to the audiovisual cues that underpin speech and language development, yet multisensory speech detection remains understudied in children with hearing loss (CHL). This research assessed detection, along with vigilant/goal-directed attention, for multisensory versus unisensory speech in CHL versus children with normal hearing (CNH). Design: Participants were 60 CHL who used hearing aids and communicated successfully aurally/orally and 60 age-matched CNH. Simple response times determined how quickly children could detect a preidentified easy-to-hear stimulus (70 dB SPL, utterance “buh” presented in auditory only [A], visual only [V], or audiovisual [AV] modes). The V mode formed two facial conditions: static versus dynamic face. Faster detection for multisensory (AV) than unisensory (A or V) input indicates multisensory facilitation. We assessed mean responses and faster versus slower responses (defined by first versus third quartiles of response-time distributions), which were respectively conceptualized as: faster responses (first quartile) reflect efficient detection with efficient vigilant/goal-directed attention and slower responses (third quartile) reflect less efficient detection associated with attentional lapses. Finally, we studied associations between these results and personal characteristics of CHL. Results: Unisensory A versus V modes: Both groups showed better detection and attention for A than V input. The A input more readily captured children’s attention and minimized attentional lapses, which supports A-bound processing even by CHL who were processing low fidelity A input. CNH and CHL did not differ in ability to detect A input at conversational speech level. Multisensory AV versus A modes: Both groups showed better detection and attention for AV than A input. The advantage for AV input was facial effect (both static and dynamic faces), a pattern suggesting that communication is a social interaction that is more than just words. Attention did not differ between groups; detection was faster in CHL than CNH for AV input, but not for A input. Associations between personal characteristics/degree of hearing loss of CHL and results: CHL with greatest deficits in detection of V input had poorest word recognition skills and CHL with greatest reduction of attentional lapses from AV input had poorest vocabulary skills. Both outcomes are consistent with the idea that CHL who are processing low fidelity A input depend disproportionately on V and AV input to learn to identify words and associate them with concepts. As CHL aged, attention to V input improved. Degree of HL did not influence results. Conclusions: Understanding speech—a daily challenge for CHL—is a complex task that demands efficient detection of and attention to AV speech cues. Our results support the clinical importance of multisensory approaches to understand and advance spoken communication by CHL. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and text of this article on the journal’s Web site (www.ear-hearing.com). ACKNOWLEDGMENTS: We thank Dr. Nancy Tye-Murray, Washington University School of Medicine (WUSM), for supervising data collection in CHL, the children and parents who participated, and the research staff who assisted: Aisha Aguilera, Carissa Dees, Nina Dinh, Nadia Dunkerton, Derek Hammons, Scott Hawkins, Brittany Hernandez, Demi Krieger, Rachel Parra McAlpine, Michelle McNeal, Jeffrey Okonye, and Kimberly Periman of UT-D (data collection, analysis, stimuli editing, computer programming) and Drs. Nancy Tye-Murray and Brent Spehar, WUSM (stimuli recording, editing). Supported by the NIDCD, grant DC-00421 to University of Texas at Dallas (UT-D). Dr. Abdi acknowledges the support of an EURIAS fellowship at the Paris Institute for Advanced Studies (France), with the support of the European Union’s 7th Framework Program for research, and funding from the French State managed by the “Agence Nationale de la Recherche (program: Investissements d’avenir, ANR-11-LABX-0027-01 Labex RFIEA+).” The authors have no conflicts of interest to disclose. Received September 25, 2018; accepted July 22, 2019. Address for correspondence: Susan Jerger, School of Behavioral Brain Sciences, GR4.1, University of Texas Dallas, 800 W. Campbell Rd, Richardson, TX 75080, USA. E-mail: sjerger@utdallas.edu Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

The Apolipoprotein Allele and Sensorineural Hearing Loss in Older Community-Dwelling Adults in Australia Objectives: Previous research has investigated whether the apolipoprotein E (APOE) ε4 allele, which is associated with an increased risk of cognitive decline, is also associated with hearing loss in older people. Results of the very limited research to date are conflicting, and sample sizes for all but one study were small. The present study aimed to investigate whether there is an association between the APOE ε4 allele and hearing loss in a large, population-based sample of community-dwelling older adults. Design: Cross-sectional audiometric data on hearing levels and APOE genotypes for 2006 participants (aged 55 to 85 years) of the Hunter Community Study were analyzed using multiple linear regression to examine the association between APOE ε4 carrier status and the 4-frequency pure-tone average (0.5 to 4 kHz) in the better hearing ear, and also across individual frequencies in the better ear. Results: Observed and expected APOE allele frequency distributions did not differ significantly overall from established general population allele frequency distributions. Unadjusted modeling using better ear pure-tone average showed a statistically significant association between APOE ε4 allele status (0, 1, 2 copies) and reduced hearing loss, but when the model was adjusted for age, this was no longer statistically significant. Across individual hearing frequencies, unadjusted regression modeling showed APOE ε4 status was significantly associated with a reduction in mean hearing thresholds at 1 and 2 kHz, but again this effect was no longer statistically significant after adjusting for age. Conclusions: The results of this study did not provide any evidence of a statistically significant association between APOE ε4 allele status and hearing loss for older adults. Further investigation of the effect of homozygous carrier status on hearing thresholds is required. ACKNOWLEDGMENTS: The authors thank the funding bodies, chief investigators, research staff, and particularly the participants of the Hunter Community Study. Supported by the University of Newcastle and the Extending Treatments, Education and Networks study, funded by the Hunter Medical Research Institute and Xstrata Coal. The authors have no conflicts of interest to disclose. Received February 12, 2019; accepted July 5, 2019. Address for correspondence: Julia Z. Sarant, Department of Audiology and Speech Pathology, 550 Swanston Street, The University of Melbourne, VIC 3010, Australia. E-mail: jsarant@unimelb.edu.au Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

Middle Ear Muscle Reflex and Word Recognition in “Normal-Hearing” Adults: Evidence for Cochlear Synaptopathy? Objectives: Permanent threshold elevation after noise exposure, ototoxic drugs, or aging is caused by loss of sensory cells; however, animal studies show that hair cell loss is often preceded by degeneration of synapses between sensory cells and auditory nerve fibers. The silencing of these neurons, especially those with high thresholds and low spontaneous rates, degrades auditory processing and may contribute to difficulties in understanding speech in noise. Although cochlear synaptopathy can be diagnosed in animals by measuring suprathreshold auditory brainstem responses, its diagnosis in humans remains a challenge. In mice, cochlear synaptopathy is also correlated with measures of middle ear muscle (MEM) reflex strength, possibly because the missing high-threshold neurons are important drivers of this reflex. The authors hypothesized that measures of the MEM reflex might be better than other assays of peripheral function in predicting difficulties hearing in difficult listening environments in human subjects. Design: The authors recruited 165 normal-hearing healthy subjects, between 18 and 63 years of age, with no history of ear or hearing problems, no history of neurologic disorders, and unremarkable otoscopic examinations. Word recognition in quiet and in difficult listening situations was measured in four ways: using isolated words from the Northwestern University auditory test number six corpus with either (a) 0 dB signal to noise, (b) 45% time compression with reverberation, or (c) 65% time compression with reverberation, and (d) with a modified version of the QuickSIN. Audiometric thresholds were assessed at standard and extended high frequencies. Outer hair cell function was assessed by distortion product otoacoustic emissions (DPOAEs). Middle ear function and reflexes were assessed using three methods: the acoustic reflex threshold as measured clinically, wideband tympanometry as measured clinically, and a custom wideband method that uses a pair of click probes flanking an ipsilateral noise elicitor. Other aspects of peripheral auditory function were assessed by measuring click-evoked gross potentials, that is, summating potential (SP) and action potential (AP) from ear canal electrodes. Results: After adjusting for age and sex, word recognition scores were uncorrelated with audiometric or DPOAE thresholds, at either standard or extended high frequencies. MEM reflex thresholds were significantly correlated with scores on isolated word recognition, but not with the modified version of the QuickSIN. The highest pairwise correlations were seen using the custom assay. AP measures were correlated with some of the word scores, but not as highly as seen for the MEM custom assay, and only if amplitude was measured from SP peak to AP peak, rather than baseline to AP peak. The highest pairwise correlations with word scores, on all four tests, were seen with the SP/AP ratio, followed closely by SP itself. When all predictor variables were combined in a stepwise multivariate regression, SP/AP dominated models for all four word score outcomes. MEM measures only enhanced the adjusted r2 values for the 45% time compression test. The only other predictors that enhanced model performance (and only for two outcome measures) were measures of interaural threshold asymmetry. Conclusions: Results suggest that, among normal-hearing subjects, there is a significant peripheral contribution to diminished hearing performance in difficult listening environments that is not captured by either threshold audiometry or DPOAEs. The significant univariate correlations between word scores and either SP/AP, SP, MEM reflex thresholds, or AP amplitudes (in that order) are consistent with a type of primary neural degeneration. However, interpretation is clouded by uncertainty as to the mix of pre- and postsynaptic contributions to the click-evoked SP. None of the assays presented here has the sensitivity to diagnose neural degeneration on a case-by-case basis; however, these tests may be useful in longitudinal studies to track accumulation of neural degeneration in individual subjects. ACKNOWLEDGMENTS: The authors gratefully acknowledge Mrs. Inge Knudson for coordinating subject recruitment. The authors thank Drs. J. J. Guinan, Jr., S. G. Kujawa, and M. D. Valero for their comments on earlier versions of this manuscript. The authors also gratefully acknowledge a gift from Decibel Therapeutics for the purchase of the commercial audiometric equipment. A.M.M. and S.A.K. performed the experiments and contributed equally to this work. K.E.H. developed software for data acquisition and analysis. K.B. and V.de.G. ran the statistical analyses. M.C.L. and S.F.M. designed the study and wrote the article. S.F.M. also performed experiments and data analysis. This work was supported by the National Institutes of Health – National Institute on Deafness and Other Communication Disorders P50 DC015857 (S.F.M., Project principal investigator (PI)) and the Lauer Tinnitus Research Center at the Massachusetts Eye & Ear (S.F.M., PI). M.C.L. is a scientific founder of Decibel Therapeutics. The other authors have no conflicts of interest to declare. Received June 20, 2018; accepted August 13, 2019 Address for correspondence: Stéphane F. Maison, Eaton-Peabody Laboratories, Massachusetts Eye & Ear, 243 Charles Street, Boston, MA 02114, USA. E-mail: stephane_maison@meei.harvard.edu Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

Rerouting Hearing Aid Systems for Overcoming Simulated Unilateral Hearing in Dynamic Listening Situations Objectives: Unilateral hearing loss increases the risk of academic and behavioral challenges for school-aged children. Previous research suggests that remote microphone (RM) systems offer the most consistent benefits for children with unilateral hearing loss in classroom environments relative to other nonsurgical interventions. However, generalizability of previous laboratory work is limited because of the specific listening situations evaluated, which often included speech and noise signals originating from the side. In addition, early studies focused on speech recognition tasks requiring limited cognitive engagement. However, those laboratory conditions do not reflect characteristics of contemporary classrooms, which are cognitively demanding and typically include multiple talkers of interest in relatively diffuse background noise. The purpose of this study was to evaluate the potential effects of rerouting amplification systems, specifically a RM system and a contralateral routing of signal (CROS) system, on speech recognition and comprehension of school-age children in a laboratory environment designed to emulate the dynamic characteristics of contemporary classrooms. It was expected that listeners would benefit from the CROS system when the head shadow limits audibility (e.g., monaural indirect listening). It was also expected that listeners would benefit from the RM system only when the RM was near the talker of interest. Design: Twenty-one children (10 to 14 years, M = 11.86) with normal hearing participated in laboratory tests of speech recognition and comprehension. Unilateral hearing loss was simulated by presenting speech-shaped masking noise to one ear via an insert earphone. Speech stimuli were presented from 1 of 4 loudspeakers located at either 0°, +45°, −90°, and −135° or 0°, −45°, +90°, and +135°. Cafeteria noise was presented from separate loudspeakers surrounding the listener. Participants repeated sentences (sentence recognition) and also answered questions after listening to an unfamiliar story (comprehension). They were tested unaided, with a RM system (microphone near the front loudspeaker), and with a CROS system (ear-level microphone on the ear with simulated hearing loss). Results: Relative to unaided listening, both rerouting systems reduced sentence recognition performance for most signals originating near the ear with normal hearing (monaural direct loudspeakers). Only the RM system improved speech recognition for midline signals, which were near the RM. Only the CROS system significantly improved speech recognition for signals originating near the ear with simulated hearing loss (monaural indirect loudspeakers). Although the benefits were generally small (approximately 6.5 percentage points), the CROS system also improved comprehension scores, which reflect overall listening across all four loudspeakers. Conversely, the RM system did not improve comprehension scores relative to unaided listening. Conclusions: Benefits of the CROS system in this study were small, specific to situations where speech is directed toward the ear with hearing loss, and relative only to a RM system utilizing one microphone. Although future study is warranted to evaluate the generalizability of the findings, the data demonstrate both CROS and RM systems are nonsurgical interventions that have the potential to improve speech recognition and comprehension for children with limited useable unilateral hearing in dynamic, noisy classroom situations. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and text of this article on the journal’s Web site (www.ear-hearing.com). ACKNOWLEDGMENTS: We thank Christine Jones, Lori Rakita, and Ora Bürkli for their insightful comments during study design. We also thank Laura Allen for consultation on the Coh-Metrix evaluation of stories used for the comprehension task. This project was funded by a grant from Sonova, AG. Portions of the project were presented at the Unilateral Hearing Loss Conference was held in Philadelphia, PA and the American Auditory Society conference was in Scottsdale, AZ sponsored by Phonak (October 22–24, 2017) and at the Scientific and Technical Conference of the American Auditory Society (March 1–3, 2018). Stimulus development for this project was supported by NIH grant P20 GM109023 (D.L.). The content of this manuscript is the responsibility and opinions of the authors and does not necessarily represent the views of the National Institutes of Health. D.L. and A.M.T. are members of the Phonak Pediatric Research Advisory Board. Received July 16, 2018; accepted July 30, 2019. Address for correspondence: Erin M. Picou, Department of Hearing and Speech Sciences, Vanderbilt University School of Medicine, 1215 21st Ave South, Room 8310, Nashville, TN 37232, USA. E-mail: erin.picou@vanderbilt.edu Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

Evaluating the Effect of Training Along With Fit Testing on Premolded Earplug Users in a Chinese Petrochemical Plant Objectives: To gain insight into the current practice of hearing protection of Chinese workers and the value of hearing protection device (HPD) fit testing. Design: HPD fit testing was conducted on workers (N = 774) in a petrochemical plant in Eastern China who were on duty during the period of this study. The 3M E-A-Rfit Dual-Ear Validation System was used to measure the personal attenuation ratings (PARs) of a premolded earplug used at the work site. Repeated fit testing was conducted at approximately 6- or 12-month intervals. Wilcoxon signed rank tests were conducted to analyze the pairwise differences between the baseline, postintervention, and follow-up visit PARs, and Mann–Whitney tests were used to compare the PARs obtained by two follow-up groups. Results: The median PAR baseline was 11 dB; significant improvement was shown on the postintervention PARs (p < 0. 001). No significant difference was shown between PARs obtained during the 6- and 12-month follow-up visits (p > 0.05). Comparing PARs of follow-up visits with the baseline PAR demonstrated a significant improvement (p < 0. 001), but revealed a significant decline (p < 0. 001) comparing with the postintervention PARs. Conclusions: HPD fit testing showed value added as to verify the sufficiency of attenuation. The training along with fit testing showed contributions to improve PARs, maintained effectiveness over time, and assisted in HPD selection. Follow-up is believed to be important to ensure that the HPDs are continually used correctly. There was no significant difference in the sustained effectiveness of the follow-up when observe 6- and 12-month subsequent to intervention. ACKNOWLEDGMENTS: We thank to Enmin Ding, Jun Wu at Jiangsu Provincial Center for Disease Control and Prevention on industrial hygiene field assistance. We’d like to express our great appreciation to Elliott H. Berger, Division Scientist of 3M Personal Safety Division for his careful review and comments from scientific point of view on this manuscript. This study was supported by the Jiangsu Provincial Outstanding Medical Academic Leader and Innovation Team (CXTDA2017029), the Natural Science Foundation of the Jiangsu Province (Grant No. BK20151594), and Personal Safety Division of 3M China Ltd. The authors have no conflicts of interest to disclose. Received April 21, 2018; accepted July 29, 2019. Address for correspondence: Yufei Liu, Personal Safety Division of 3M China Ltd., 3/F, 3M Guangzhou Plant, No. 9, Nanxiang Er Road, Science City, Guangzhou, People’s Republic of China. E-mail: sliu9@mmm.com Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

Acoustic Hearing Can Interfere With Single-Sided Deafness Cochlear-Implant Speech Perception Objectives: Cochlear implants (CIs) restore some spatial advantages for speech understanding in noise to individuals with single-sided deafness (SSD). In addition to a head-shadow advantage when the CI ear has a better signal-to-noise ratio, a CI can also provide a binaural advantage in certain situations, facilitating the perceptual separation of spatially separated concurrent voices. While some bilateral-CI listeners show a similar binaural advantage, bilateral-CI listeners with relatively large asymmetries in monaural speech understanding can instead experience contralateral speech interference. Based on the interference previously observed for asymmetric bilateral-CI listeners, this study tested the hypothesis that in a multiple-talker situation, the acoustic ear would interfere with rather than improve CI speech understanding for SSD-CI listeners. Design: Experiment 1 measured CI-ear speech understanding in the presence of competing speech or noise for 13 SSD-CI listeners. Target speech from the closed-set coordinate response-measure corpus was presented to the CI ear along with one same-gender competing talker or stationary noise at target-to-masker ratios between −8 and 20 dB. The acoustic ear was presented with silence (monaural condition) or with a copy of the competing speech or noise (bilateral condition). Experiment 2 tested a subset of 6 listeners in the reverse configuration for which SSD-CI listeners have previously shown a binaural benefit (target and competing speech presented to the acoustic ear; silence or competing speech presented to the CI ear). Experiment 3 examined the possible influence of a methodological difference between experiments 1 and 2: whether the competing talker spoke keywords that were inside or outside the response set. For each experiment, the data were analyzed using repeated-measures logistic regression. For experiment 1, a correlation analysis compared the difference between bilateral and monaural speech-understanding scores to several listener-specific factors: speech understanding in the CI ear, preimplantation duration of deafness, duration of CI experience, ear of deafness (left/right), acoustic-ear audiometric thresholds, and listener age. Results: In experiment 1, presenting a copy of the competing speech to the acoustic ear reduced CI speech-understanding scores for target-to-masker ratios ≥4 dB. This interference effect was limited to competing-speech conditions and was not observed for a noise masker. There was dramatic intersubject variability in the magnitude of the interference (range: 1 to 43 rationalized arcsine units), which was found to be significantly correlated with listener age. The interference effect contrasted sharply with the reverse configuration (experiment 2), whereby presenting a copy of the competing speech to the contralateral CI ear significantly improved performance relative to monaural acoustic-ear performance. Keyword condition (experiment 3) did not influence the observed pattern of interference. Conclusions: Most SSD-CI listeners experienced interference when they attended to the CI ear and competing speech was added to the acoustic ear, although there was a large amount of intersubject variability in the magnitude of the effect, with older listeners particularly susceptible to interference. While further research is needed to investigate these effects under free-field listening conditions, these results suggest that for certain spatial configurations in a multiple-talker situation, contralateral speech interference could reduce the benefit that an SSD-CI otherwise provides. ACKNOWLEDGMENTS: We thank Cochlear Ltd. and Med-El for providing the testing equipment and technical support. The research reported in this publication was supported by the National Institute on Deafness and other Communication Disorders of the National Institutes of Health under Award Number R01 DC015798 (J.G.W.B. and M.J.G.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The views expressed in this article are those of the authors and do not reflect the official policy of the Department of Army/Navy/Air Force, Department of Defense, or US Government. The identification of specific products or scientific instrumentation does not constitute endorsement or implied endorsement on the part of the author, Department of Defense, or any component agency. Portions of this article were presented at the Midwinter Meeting of the Association for Research in Otolaryngology, Baltimore, MD, February 2017, the 173rd Meeting of the Acoustical Society of America, Boston, MA, June 2017, and the Conference on Implantable Auditory Prostheses, Tahoe City, CA, July 2019. J.G.W.B., O.A.S., and M.J.G. designed the experiments; J.G.W.B., O.A.S., and K.K.J. recruited listeners and collected the data; J.G.W.B. analyzed the data; J.G.W.B., O.A.S., K.K.J., and M.J.G. wrote the article. All authors discussed the results and implications and commented on the manuscript at all stages. The authors have no conflicts of interest to disclose. Received January 15, 2019; accepted August 14, 2019. Address for correspondence: Joshua G. W. Bernstein, National Military Audiology and Speech Pathology Center, Walter Reed National Military Medical Center, 4954 N. Palmer Rd., Bethesda, MD 20889, USA. E-mail: joshua.g.bernstein.civ@mail.mil Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

Observations of Distortion Product Otoacoustic Emission Components in Adults With Hearing Loss Objectives: Distortion product otoacoustic emissions (DPOAEs) measured in the ear canal are composed of OAEs generated by at least two mechanisms coming from different places in the cochlea. Otoacoustic emission (OAE) models hypothesize that reduction of cochlear gain will differentially impact the components. The purpose of the current experiment was to provide preliminary data about DPOAE components in adults with hearing loss in relation to OAE models and explore whether evaluation of the relative amplitudes of generator and reflection components can enhance identification of hearing loss. Design: DPOAEs were measured from 45 adult ears; 21 had normal hearing (≤15 dB HL) and 24 with mild-to-severe sensorineural hearing loss (>15 dB HL). The higher frequency primary (f2) was swept logarithmically between 1500 and 6000 Hz, and f2/f1 was 1.22. The two equal-level primaries varied from 55 to 75 dB SPL in 5 dB steps. The swept primary procedure permitted the measurement of the amplitude and phase of the DPOAE fine structure and the extraction of the two major components (generator and reflection) by varying the predicted delays of the analysis windows. Results: DPOAE fine structure was reduced or absent in ears with hearing loss. DPOAE generator and reflection components were lower in ears with hearing loss than those with normal hearing, especially for the reflection component. Significant correlations were found between the generator component and hearing threshold but not between reflection levels and hearing threshold. Most ears with normal hearing had both components, but only a small number of ears with hearing loss had both components. Conclusions: The reflection component is not recordable or low in level in ears with hearing loss, explaining the reduced or absent DPOAE fine structure. DPOAE generator components are also lower in level in ears with hearing loss than in ears without hearing loss. In ears that had both measurable generator and reflection components, the relationship between the two did not depend on the presence or absence of hearing loss. Because reflection components are not measurable in many ears with hearing thresholds >15 dB HL, stimuli that evoke other types of reflection emissions, such as stimulus-frequency or long-latency transient-evoked emissions, should be explored in conjunction with DPOAE generator components. ACKNOWLEDGMENTS: The authors thank Lisa Lamson, Stefania Arduini, and Devon Pacheco for article preparation. This research was funded by the March of Dimes Birth Defects Foundation. The authors have no conflicts of interest to disclose. Received May 3, 2018; accepted July 15, 2019. Address for correspondence: Beth A. Prieve, Department of Communication Sciences and Disorders, Syracuse University, 621 Skytop Road, Syracuse, NY 13244, USA. E-mail:baprieve@syr.edu. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.