Increasing Hearing Readiness Using Boothless Audiometry.

INTRODUCTION: U.S. Army regulations require all soldiers to undergo annual audiometric testing to maintain hearing readiness. The standard method of monitoring hearing in the DoD is via multi-person testing in sound-treated booths using the Defense Occupational and Environmental Health Readiness System-Hearing Conservation. COVID-19 significantly hindered the standard method, resulting in alarming declines in hearing readiness. In response, the Army Hearing Program initiated a pilot program to use boothless audiometers to supplement standard methods to increase hearing readiness. MATERIALS AND METHODS: Funding from the Coronavirus Aid, Relief, and Economic Security Act was used to purchase 169 boothless audiometers and increase staffing at dozens of Army Hearing Program clinics. Standard operating procedures were established for audiometric testing outside the booth using a process matching standard test parameters (i.e., test frequencies, tone characteristics, and interstimulus intervals). Additional capabilities developed to leverage this new technology during the annual hearing exam include the administration of automated contralateral masking, enhanced tinnitus screening, and hearing health education and training. RESULTS: Monitoring audiometry using boothless audiometers has been conducted for nearly 12,000 service members worldwide. Thresholds obtained via boothless audiometers are comparable to follow-up thresholds obtained from the standard test methods in the booth (mean difference 95% CI, -1.2, 0.9), and hearing readiness has returned to pre-pandemic levels at installations where this novel technology is being used regularly. CONCLUSIONS: Significant reductions in patient encounters as a direct result of the COVID-19 pandemic have led to innovative solutions leveraging boothless audiometers. While this has aided the primary mission to maintain a medically ready force, innovations from this endeavor highlight several additional improvements relative to current standards of care that should be considered for permanent inclusion in DoD Hearing Conservation Programs.

Rapid Assessment of Subjective Hearing Complaints With a Modified Version of the Tinnitus and Hearing Survey.

Hearing difficulties are frequently reported by patients in audiology clinics, including patients with normal audiometric thresholds. However, because all individuals experience some difficulty understanding speech in noisy environments, it can be difficult to assess hearing complaints objectively across patients. Normative values help address this issue by providing an objective cutoff score for determining what is or is not clinically significant. The goal of this study was to establish normative values for the four-item hearing subscale of the Tinnitus and Hearing Survey (THS-H). Respondents completing the THS-H rate the level of difficulty understanding speech in the situations most commonly reported as being difficult: in the presence of noise, on TV or in movies, soft voices and group conversations. In this study, 22,583 US Service Members (SMs) completed the THS-H using an 11-point scale ranging from 0 (not a problem) to 10 (a very big problem). Responses to the four items were summed to produce values between 0 and 40. The distribution of the final scores was analyzed based on severity of hearing loss, age, and sex. Only 5% of SMs with clinically normal hearing scored above 27, so this score was selected as a cutoff for "clinically significant hearing problems." Due to its ease of administration and interpretation, the THS-H could be a useful tool for identifying patients with subjective hearing difficulty warranting audiological evaluation and management.

Developing an Evidence-Based Military Auditory Fitness-for-Duty Standard Based on the 80-Word Modified Rhyme Test.

OBJECTIVES: One important function of military audiology is to conduct evaluations of service members (SMs) with hearing loss to ensure they are fit for deployment in dangerous operational environments. The objective of this study was to establish evidence-based auditory fitness-for-duty criteria based on speech-in-noise performance on the 80- and 160-word clinical versions of the Modified Rhyme Test (MRT 80 and MRT 160 ). DESIGN: Approximately 2400 SMs with various levels of hearing loss were recruited to complete the MRT 80 in conjunction with their annual hearing conservation evaluations. These SMs were also asked to perform one or more operationally-relevant listening tasks based on audio recordings made in highly realistic military training environments. The scores on these tests were compared to determine how well a proposed cutoff criterion for the MRT 80 was able to identify individuals who are hard of hearing with an exceptionally high risk of abnormally poor performance on operationally-relevant hearing tasks. RESULTS: The results show that a cutoff criterion that combines the percent correct score on two lists of the MRT 80 (i.e. MRT 160 ) with information about the better-ear threshold at 2 kHz is generally able to separate listeners with hearing loss into those who are likely to perform relatively well on operational listening tests and those who are likely to perform poorly on these tasks. This is consistent with current military acquisition standards, which identify the MRT as the preferred test for evaluating speech intelligibility for radios, headsets, and other communication equipment. It is also consistent with prior studies conducted in high-fidelity military simulations which have shown a significant correlation between MRT performance and operational outcomes. CONCLUSIONS: The proposed selection criteria, along with the new hearing profile standards that were recently adopted by the US Army, appear to provide an effective evidence-based methodology for identifying those SMs with hearing loss who are most at risk for poor performance on hearing-critical military tasks.

Development and Evaluation of a Body-Worn Dosimeter for Continuous and Impulsive Noise.

Noise exposure is encountered nearly everyday in both recreational and occupational settings, and can lead to a number of health concerns including hearing-loss, tinnitus, social-isolation and possibly dementia. Although guidelines exist to protect workers from noise, it remains a challenge to accurately quantify the noise exposure experienced by an individual due to the complexity and non-stationarity of noise sources. This is especially true for impulsive noise sources, such as weapons fire and industrial impact noise which are difficult to quantify due to technical challenges relating to sensor design and size, weight and power requirements. Because of this, personal noise dosimeters are often limited to a maximum 140 dB SPL and are not sufficient to measure impulse noise. This work details the design of a body-worn noise dosimeter (mNOISE) that processes both impulse and continuous noise ranging in level from 40 dBA-185 dBP (i.e. a quiet whisper to a shoulder fired rocket). Also detailed is the capability of the device to log the kurtosis of the sound pressure waveform in real-time, which is thought to be useful in characterizing complex noise exposures. Finally, we demonstrate the use of mNOISE in a military-flight noise environment. Clinical Relevance- On-body noise exposure monitoring can be used by audiologists industrial hygiene personnel and others to determine threshold of injury adequate hearing protection requirements and ultimately reduce permanent noise-induced hearing loss.

Reference equivalent threshold sound pressure levels for the Wireless Automated Hearing Test System.

This paper presents reference equivalent threshold sound pressure levels (RETSPLs) for the Wireless Automated Hearing Test System (WAHTS), a recently commercialized device developed for use as a boothless audiometer. Two initial studies were conducted following the ISO 389-9 standard [ISO 389-9 (2009). "Acoustics-Reference zero for the calibration of audiometric equipment. Part 9: Preferred test conditions for the determinations of reference hearing threshold levels" (International Organization for Standardization, Geneva)]. Although the standard recruitment criteria are intended to yield otologically normal test subjects, the recruited populations appeared to have slightly elevated thresholds [5-10 dB hearing level (HL)]. Comparison of WAHTS thresholds to other clinical audiometric equipment revealed bias errors that were consistent with the elevated thresholds of the RETSPL populations. As the objective of RETSPLs is to ensure consistent thresholds regardless of the equipment, this paper presents the RETSPLs initially obtained following ISO 389-9:2009 and suggested correction to account for the elevated HLs of the originally recruited populations. Two additional independent studies demonstrate the validity of these corrected thresholds.

Relationship Between Subjective Reports of Temporary Threshold Shift and the Prevalence of Hearing Problems in Military Personnel.

Traditional hearing conservation programs are based on the premise that noise dose, as measured by the time-weighted average noise level, is the primary risk factor associated with occupational hearing loss and that permanent threshold shifts are the most relevant outcome measures for determining when a noise-related hearing loss has occurred. However, recent studies in animal models have suggested that significant neurological damage to the hearing system can occur from noise exposures even when they are not severe enough to result in permanent threshold shifts. This has led to a number of studies attempting to relate subjective measures of noise exposure to subjective measures of hearing difficulty and suprathreshold measures of hearing performance (e.g., speech-in-noise tests). In this study, 3,330 U.S. service members volunteered to complete a survey on noise exposure, subjective hearing complaints, and tinnitus in conjunction with their annual hearing tests. Two questions were also included about the frequency and duration of temporary hearing losses that may have been experienced by the service member. The results show that subjective reports of temporary threshold shifts were substantially more predictive of tinnitus and other hearing complaints than more traditional questions based on the frequency of noise exposure.

The Effects of Blast-Related Neurotrauma on Aurally Aided Visual Search While Standing and Walking.

Service members (SMs) who have suffered mild traumatic brain injury due to blast exposure (b/TBI) often report post-concussive symptoms consistent with auditory, visual, or vestibular impairments even when they score within the normal range on traditional clinical tests of sensory function. One possible explanation for this discrepancy is that patients who score in the low normal range in more than one sensory modality may be severely impaired in tasks that require multisensory integration. This study evaluated unimodal and multimodal sensory performance in SMs with b/TBI and healthy controls by having them conduct four tasks while walking or standing in an immersive virtual environment: an Auditory Localization task (AL) where they moved a cursor to the perceived location of a sound; a Visual Discrimination task (VD) where they distinguished between two visual targets; an Aurally-Aided Visual Search Task (AAVS) where they used an auditory cue to locate and identify a visual target hidden in a field of visual distractors; and a Visual-Only Visual Search task (VOVS) where they located and identified a visual target in a field of distractors with no auditory cue. The results show the b/TBI and healthy control groups performed equivalently in the AL and VD tasks, but that the b/TBI group responded roughly 15% slower in the AAVS task and 50% slower in the VOVS task. Walking had no effect on performance in the visual-only tasks, but both groups responded faster while walking in the AL and AAVS tasks without any reduction in accuracy.

Using tablet-based technology to deliver time-efficient ototoxicity monitoring.

OBJECTIVE: The goal of this article is to highlight mobile technology that is not yet standard of care but could be considered for use in an ototoxicity monitoring programme (OMP) as an adjunct to traditional audiometric testing. Current guidelines for ototoxicity monitoring include extensive test protocols performed by an audiologist in an audiometric booth. This approach is comprehensive, but it may be taxing for patients suffering from life-threatening illnesses and cost prohibitive if it requires serial clinical appointments. With the use of mobile technology, testing outside of the confines of the audiometric booth may be possible, which could create more efficient and less burdensome OMPs. DESIGN: A non-systematic review of new OMP technology was performed. Experts were canvassed regarding the impact of new technology on OMPs. STUDY SAMPLE: OMP devices and technologies that are commercially available and discussed in the literature. RESULTS: The benefits and limitations of portable, tablet-based technology that can be deployed for efficient ototoxicity monitoring are discussed. CONCLUSIONS: New mobile technology has the potential to influence the development and implementation of OMPs and lower barriers to patient access by providing time efficient, portable and self-administered testing options for use in the clinic and in the patient's home.

Effects of masker type, sentence context, and listener age on speech recognition performance in 1-back listening tasks.

Studies have shown that older listeners with normal hearing have greater difficulty understanding speech in noisy environments than younger listeners even during simple assessments where listeners respond to auditory stimuli immediately after presentation. Older listeners may have increased difficulty understanding speech in challenging listening situations that require the recall of prior sentences during the presentation of new auditory stimuli. This study compared the performance of older and younger normal-hearing listeners in 0-back trials, which required listeners to respond to the most recent sentence, and 1-back trials, which required the recall of the sentence preceding the most recent. Speech stimuli were high-context and anomalous sentences with four types of maskers. The results show that older listeners have greater difficulty in the 1-back task than younger listeners with all masker types, even when SNR was adjusted to produce 80% correct performance in the 0-back task for both groups. The differences between the groups in the 1-back task may be explained by differences in working memory for the noise and spatially separated speech maskers but not in the conditions with co-located speech maskers, suggesting that older listeners have increased difficulty in memory-intensive speech perception tasks involving high levels of informational masking.

Sensitivity of school-aged children to pitch-related cues.

Two experiments investigated the ability of 17 school-aged children to process purely temporal and spectro-temporal cues that signal changes in pitch. Percentage correct was measured for the discrimination of sinusoidal amplitude modulation rate (AMR) of broadband noise in experiment 1 and for the discrimination of fundamental frequency (F0) of broadband sine-phase harmonic complexes in experiment 2. The reference AMR was 100 Hz as was the reference F0. A child-friendly interface helped listeners to remain attentive to the task. Data were fitted using a maximum-likelihood technique that extracted threshold, slope, and lapse rate. All thresholds were subsequently standardized to a common d' value equal to 0.77. There were relatively large individual differences across listeners: eight had relatively adult-like thresholds in both tasks and nine had higher thresholds. However, these individual differences did not vary systematically with age, over the span of 6-16 yr. Thresholds were correlated across the two tasks and were about nine times finer for F0 discrimination than for AMR discrimination as has been previously observed in adults.

Short-term adaptation to accented English by younger and older adults.

This study examined the effects of age and hearing loss on short-term adaptation to accented speech. Data from younger and older listeners in a prior investigation [Gordon-Salant et al. (2010). J. Acoust. Soc. Am. 128, 444-455] were re-analyzed to examine changes in recognition over four administrations of equivalent lists of English stimuli recorded by native speakers of Spanish and English. Results showed improvement in recognition scores over four list administrations for the accented stimuli but not for the native English stimuli. Group effects emerged but were not involved in any interactions, suggesting that short-term adaptation to accented speech is preserved with aging and with hearing loss.