2025 NHCA Annual Conference

The selection of appropriate hearing protection devices (HPDs) is crucial for safeguarding against hazardous noise exposure and preventing noise-induced hearing loss. Traditional selection methods primarily rely on the Noise Reduction Rating (NRR), often neglecting other factors. To improve upon these methods, an interactive software platform, the Hearing Protection Optimization Tool (HPOT), was developed to guide HPD selection. The HPOT down-selects HPDs using performance metrics derived from laboratory-based, electromechanical tests. These electromechanical tests have been validated against human subject performance and quantify the adverse effects of HPDs on sound localization, speech intelligibility, self-noise, and level-dependent attenuation. User input indicates the importance of each aspect of performance for their specific application and the software generates a ranked list of the HPD options that best meet both attenuation requirements and desired performance characteristics. The recommendations can be further refined based on logistical constraints such as power requirements, compatibility with additional protective equipment, form factor preferences, and cost. The HPOT significantly advances hearing conservation efforts by eliminating the guesswork in the HPD selection process, allowing users to make informed choices based on objective measures that best align with their protection goals.

Learning Objectives:
1. Discuss the importance of hearing protection performance metrics and their role in optimizing HPD selection.
2. Explain the importance of HPD selection by discussing the limitations of traditional methods and how these limitations can affect auditory perception and protection outcomes.
3. Demonstrate the use of a software tool in prioritizing various HPD performance metrics for specific industrial tasks to recommend the most appropriate HPDs.

As OSHA standards continue to shape workplace safety protocols, the ability to deliver compliant, reliable, and innovative hearing conservation solutions is more critical than ever. This presentation will delve into the latest advancements in digital audiometry, with a focus on how these technologies can support organizations in meeting OSHA’s requirements. We will explore the latest updates to hearX’s Hearing Conservation solution, which enables compliance at lower cost with more efficient testing and secure cloud data management without needing a traditional sound booth.

Additionally, the session will address the need for rigorous data protection certifications that not only secure sensitive employee information but also ensure full compliance with HIPAA and other relevant regulations. Finally, our presenter will introduce recent enhancements to our cloud-based data management system, designed to streamline reporting and operational efficiency, providing actionable insights supporting compliance and improved employee health outcomes.

Learning Objectives:
1. Compare traditional in-booth audiometry with boothless digital solutions and evaluate their respective roles in ensuring OSHA compliance.
2. Explain the critical importance of data protection within hearing conservation programs and describe the necessary steps to ensure HIPAA compliance.
3. Analyze the effects of ambient noise on hearing test accuracy and define how our boothless technology effectively mitigates these challenges, supporting compliance in real-world occupational health settings.

Level-dependent hearing protectors enable to perceive or even amplify soft to medium-level sounds, while protecting the ear against damaging high-level signals. This study investigates the effect of two level-dependent hearing protection devices on localization performance with two different warnings signals in noise. In a listening test with 16 normal-hearing subjects inside a horizontal array of 48 loudspeakers, localization performance dropped using earmuffs. In the most extreme cases, signals where perceived as coming from the opposite direction.
In addition, the stimuli used in the experiment were recorded with an artificial head in the same measurement setup to calculate the corresponding interaural cues. The technical measurements support the findings of the hearing study by revealing large changes of interaural level differences with earmuffs compared to open ears that were mostly in line with the subjects’ response. Finally, current localization models were run with the recordings to check their performance and predictions with the tested warning signals.
These findings indicate that it is critical to test electronic hearing protectors on changed interaural cues to avoid safety risks due to impaired localization. In addition, measurements of these cues can help predicting the perceived sound direction by human listeners, e.g., by modelling the possible outcomes.

Learning Objectives:
1. Describe possible safety risks of level-dependent hearing protectors.
2. Recall at least two ways to analyze the localization performance in listening tests.
3. Discuss the limitations of current sound localization models.

Conducting a hearing conservation testing program without a sound booth is possible with boothless audiometers. Dr. Victoria Bugtong, Au.D., a former Department of Defense (DOD) Audiologist, shares successes and challenges with setting up and maintaining a permanent boothless hearing conservation testing program. The presentation will guide you through the steps for taking the testing mission out of the sound isolation booth and successfully bringing it to any temporary testing event. The presentation covers all aspects of implementing boothless audiometry in the DOD from preparation, set up, ambient noise considerations, patient documentation and data entry. Dr. Bugtong will share the patient testing processes, and the lessons learned from her years working with boothless audiometers.

Learning Objectives:
1. Recognize how boothless audiometry is being used successfully in existing hearing conservation programs.
2. Summarize the benefits of implementing boothless audiometry technology in a DOD hearing conservation program.
3. Create and plan procedure for a permanent or temporary hearing conservation program using boothless audiometry.

Around 9 million Americans currently face the hazard of noise induced hearing loss (Dobie, 2008). Personal Attenuation Ratings (PAR) reflect the custom attenuation provided by ear plugs and can be helpful in implementing hearing conservation programs in industrial settings. PAR ratings can be confounded by lack of instruction on self insertion of ear plugs. Differences in shape and size of ear canals also play a role. The purpose of the current study was to evaluate PARs obtained from paper mill workers. PARs from paper mill workers were compared to a control group comprised of AuD students enrolled in a hearing conservation course. Audiograms and PARs were obtained from 10 paper mills workers after self insertion of ear plugs. A WAHTs system was used to collect the data. The audiometric data was used to compile information on years lived with disability (YLD). Mill workers exhibited high YLD. Statistical analysis was performed using independent samples T test to compare two groups, paper mill workers vs. controls. T test results showed that the PAR values were significantly reduced in paper mill workers, relatively to controls (T= -7.44; P <.001). These results illustrate the importance of experience required in self insertion of ear plugs.

Learning Objectives:
1. Describe the importance of personal attenuation ratings
2. Recognize the variability and problems associated with PAR values
3. Identify the value in experience and training in self insertion of ear plugs

In-ear noise dosimetry offers benefits over traditional free-field or body-worn dosimetry because in-ear dosimeters measure actual noise exposure, including the as-worn attenuation provided by the subject’s hearing protection. Furthermore, impulse sounds may be accurately captured with microphones that have lower dynamic range and bandwidth requirements than those needed for freestream or body-worn dosimeters because the hearing protection moderates the peak levels and frequency characteristics of impulse sound waves.
However, there are challenges to the use of in-ear dosimeters. The microphone must be integrated into an eartip that is comfortable and easy to use. The sound level measured by the ear-canal microphone should be related to the level at the eardrum and to the free-field, which is the level on which current permissible exposures are based. If the hearing protection device provides communications or a transparent hear-through mode, then any coupling between the microphone and speaker must be addressed. Consideration should also be given to artifacts induced by knocks or cable noise and to the effect of the wearer’s voice or other body noises.
The practical benefits, challenges and constraints of in-ear dosimeters are presented through a discussion of the development and testing of a wireless in-ear dosimeter.

Learning Objectives:
1. Describe the differences between in-ear, body-worn, and free-field dosimeters.
2. Explain the relevance of noise levels measured at microphone, eardrum, and free-field reference points to permissible exposure limits.
3. Compare and contrast the characteristics of impulse sound waves measured inside hearing protection in the ear to those measured in the free field.

The assessment of sound exposure from communication devices and earphones typically requires specialized measurement methods such as the microphone in the real-ear technique or the use of manikins or artificial ears. In practice, however, such assessments are challenging to deploy in most workplaces and are often not conducted on a regular basis due to lack of proper equipment and/or expertise. A simple calculation method has been devised that only requires widely accessible equipment (e.g. sound level meter or noise dosimeter) together with basic information about the devices worn (e.g., attenuation) and the communication or listening task (e.g., duration of listening within the work shift). The calculation method, specified in Canadian standard Z107.56, is intended to increase accessibility to communication device and earphone sound exposure assessments to the widest range of stakeholders in hearing loss prevention. The method brings together the many factors contributing to communication devices and earphone sound exposure and thus it is also useful when examining possible exposure mitigation measures. This paper will present the calculation method and provide examples of its uses.

Learning Objectives:
1. Describe the measurement challenges when assessing sound exposure from communication devices and earphones
2. Explain the relevance of noise levels measured at microphone, eardrum, and free-field reference points to permissible exposure limits.
3. Compare and contrast the characteristics of impulse sound waves measured inside hearing protection in the ear to those measured in the free field.

A Hybrid Model of Presenting Dangerous Decibels to Multiple Classrooms Simultaneously
Valerie Pavlovich Ruff, AuD, Sharon Sandridge, Ph.D.
Descriptives of cohort one participants in the Apple Hearing Study
Lauren M. Smith, MS, MPH, COHC
Evaluating the Necessity of Follow-Up Test Two in DoD Hearing Conservation Protocol
John Foster, Lt Col, AuD, MSPH, Jennifer Sweny, AuD
Hearing Loss and Physical Activity in Aging Farmers
Jan Moore, Ph.D.
Investigation of Spatial Memory and Learning Skills in Rats with Unilateral Mild-Moderate Congenital Hearing Loss: A Preliminary Behavioral Study
FATMA NUR KOMUR, MSc., OZLEM TUGCE CILINGIR KAYA, Ph.D., AYCA CIPRUT, Ph.D., AYSE NUR YAVUZ, Ph.D., ALI CEMAL YUMUSAKHUYLU, Ph.D.
Exploration of Prevalence, Progression, and Prevention of Hearing Loss in Osteogenesis Imperfecta Types III and IV by COL1A1 and COL1A2 mutations.
Julie Christensen, M.S.
Sound exposure and hearing protection: A survey of electronic dance music attendees
Hannah Miller, BA
Speech Intelligibility and Phonemic Errors in Veterans with Sensorineural Hearing Loss
Madison Aivaz, B.S., Sridhar Krishnamurti, Ph.D, Kathleen McDevitt, Undergraduate Student
The Role of Music Educators in Hearing Loss Prevention
Blake Voss, B.S.
Influence of reference transducer location on hearing protector attenuation metrics for impulse noise
William J. Murphy, Ph.D.
Evaluation and Comparison of Hearing Protector Training Methods
William J. Murphy, Ph.D.

Click here to read poster descriptions and learning objectives.

“Why Is Everything So Loud” is a question I have been asking myself for many years. It didn’t used to be this way. Since the evolution of humans, loudness has steadily grown and has become engrained in society. How has loudness affected us, how did we accommodate loudness in our lives, and what we can expect in the future? Also, we’ll discuss “quiet,” define it, why quiet is important, and how to achieve it in our daily life.

Learning Objectives:
1. Define "loudness" and differentiate it from noise.
2. Identify those factors that have increased loudness over time.
3. List the long term benefits of "quiet."

Bose A20 headsets are commonplace in aviation; however, the new A30 headset is set to replace them. Aviation headsets serve as communication devices, while allowing for hearing protection. Real-Ear Attenuation at Threshold is a standard measure for determining the passive attenuation of hearing protectors and has strict room requirements for conducting measurements. Field Attenuation Estimation Systems are gaining interest to assess fit for hearing protectors in the operational community, but are limited by the inability to assess over-the-ear hearing protectors. A proposed method of utilizing the WAHTS audiometer with the headset positioned around the neck to conduct psychoacoustic measurements. This study compares standard REAT measurements to the proposed fit check method to assess the passive attenuation of the Bose A30. We will compare the frequency-specific attenuation and calculate the Personal Attenuation Rating for each method. Total attenuation will be reported as well for the Bose A30.

Data analyses will be complete prior to the conference. We anticipate findings of similar nature for REAT and fit testing methods to identify the passive attenuation level of the Bose A30. Outcomes will be used to validate a correction factor for the neck-based procedure due to the level difference between on-ear versus on-neck configurations.

Learning Objectives:
1. Identify purpose of FAES and how it can be utilized with headphone HPDs.
2. Compare noise attenuation metrics with noise cancellation on to those with noise cancellation off.
3. Recognize the benefit of FAES when in aviation setting.

Hearing protector fit testing (HPFT) provides a substantial opportunity for the Department of Defense (DOD) to improve its hearing conservation program (HCP). HPFT ensures individuals are trained to correctly insert their hearing protectors so that they have a hearing protector that provides an appropriate level of protection. The ability to hear and communicate is vital to mission accomplishment, and when auditory function is impaired, critical safety and performance is degraded. Service members and noise-exposed civilians are at significant risk for noise-induced hearing loss.
DOD policy requires the incorporation of HPFT into their HCPs. The development of a HPFT task force (TF), led by the Defense Health Agency, Hearing Center of Excellence, will expedite the adoption of this requirement. The TF will ensure a consistent program with respect to equipment, training, public health studies, and recordkeeping. Coordination and collaboration between the DOD and its component organizations supports effective, cohesive, and comprehensive HPFT implementation. This talk will address successes, challenges, and best practices associated with the development of implementation plans, establishment of equipment, training, and information technology requirements, and development of research plans to address gaps for DOD large-scale HPFT program implementation.

Learning Objectives:
1. List the four sub-task forces established by the DOD to implement hearing protector fit testing.
2. Describe three challenges associated with large-scale hearing protector fit testing implementation.
3. Name the DOD record keeping form used to collect hearing protector fit testing data for Service members and noise-exposed civilian employees.

Subjective methods to conduct hearing protector fit testing and booth-less audiometry assess hearing thresholds for unoccluded and occluded conditions. During a 2012 NIOSH field evaluation of hearing protection fit testing with HPD Well-Fit™, workers’ personal attenuation ratings (PAR) were tested in four locations (two conference rooms and two small offices). During testing, the ambient noise levels were captured every ten seconds and the timestamps for each threshold identification were recorded with 1-second resolution. The clocks on the computers and the sound level meters were synchronized prior to commencing the field study. The one-third-octave-band noise levels from 20 to 20,000 Hz were logged and compared with the hearing thresholds measured at 500, 1,000, and 2,000 Hz. Ambient background noise may have masked the 500 Hz thresholds for the unoccluded ears more than the thresholds for 1,000 and 2,000 Hz. This paper will consider the potential effects on the overall three-frequency PAR and propose methods to monitor ambient noise.

Learning Objectives:
1. Explain the effects of ambient background noise on hearing tests for fit-testing and boothless audiometry and measurement techniques to assess and analyze ambient background noise.
2. Describe a case study where background noise was measured during the course a study on hearing protector fit testing.
3. Apply measurements of background noise to determine whether their hearing tests may have been affected by masking due to elevated background noise.

Hearing protector fit testing (HPFT) measures the amount of attenuation a hearing protector provides while it is being worn. Recent Department of Defense (DOD) policy changes mandating HPFT for certain noise-exposed personnel assume that a significant portion of hearing damage is directly related to poorly fit hearing protectors. However, there is limited direct evidence supporting the effectiveness of HPFT in reducing service-related auditory injuries in the military. Additionally, current HPFT methods are not appropriate for all hearing protector styles.

This presentation will highlight ongoing efforts to improve hearing health and readiness in the military by implementing HPFT in various contexts within DOD Hearing Conservation Programs. It will discuss current findings investigating the relationship between personal attenuation rating (PAR) and various hearing health outcomes (e.g., hearing threshold shifts, noise exposure history, and hearing difficulties). The overarching goal is to transition knowledge from this project to assess the feasibility of a minimal acceptable PAR standard, identify key hearing protection fitting behaviors for standardized education, and underscore the importance of incorporating HPFT within DOD hearing conservation.

The views expressed in this abstract are those of the authors and do not necessarily reflect the official policy of the Department of Defense or U.S. Government.

Learning Objectives:
1. Summarize PAR performance across performance sites and hearing health outcomes.
2. Identify obstacles in implementing HPFT as reported by clinicians.
3. Describe the relationship between PAR and significant threshold shifts.

The Department of Defense (DOD) has implemented new requirements under Instruction 6055.12 for comprehensive hearing conservation programs (HCPs) to protect military personnel from hearing loss. These regulations mandate the use of hearing protection devices (HPDs) as well as their proper fit, particularly for those individuals exposed to hazardous noise or experiencing significant changes in hearing thresholds. To meet these evolving needs, there is a demand for integrated test systems that combine both hearing- and fit-testing capabilities to enhance efficiency and compliance. This presentation will explore the broader challenges of implementing large-scale, effective fit testing and examine an innovative solution that can streamline these processes. We will introduce a new approach to integrating fit testing instructions into the Wireless Automated Hearing Test System (WAHTS) mobile app, as a potential solution to HCP needs. By allowing for asynchronous, multi-user testing with minimal administrative oversight, and providing personalized, interactive education and re-instruction, WAHTS’ new app enables a model for reducing time, personnel, and costs. The discussion will highlight how these technological advancements align with the DOD's commitment to protecting hearing health while optimizing operational efficiency.

Learning Objectives:
1. Describe the types of instructions commonly used to help improve an individual’s ability to insert their earplugs
2. Identify the new DOD requirements for HCPs and how fit testing fits within current OSHA regulations
3. Evaluate the challenges and opportunities associated with largescale fit testing

The November 22, 2023 update to Department of Defense (DOD) Instruction 6055.12, "Hearing Conservation Program" promulgates a significant new requirement for hearing protector fit testing to be conducted for all DOD personnel who have noise exposures greater than or equal to 95 dBA 8-hour time weighted average (TWA) and who are enrolled in a service hearing conservation program (HCP).  This requires multi-frequency REAT or MIRE testing to identify the need for earplug fit training or alternative earplugs for an individual, which imposes significant time and instrumentation in the field setting.  A new acoustical physical methodology has been developed to precede in-field REAT or MIRE, not requiring REAT’s threshold tests or MIRE’s in/under-earplug microphones. The Leak-and-Attenuation Test (LAT) comprises an special instrumented headphone worn over the occluding earplug, and via analysis of resonance and sound path lengths that reflect the quality of an earplug’s seal, leaks are identified in a few seconds without requiring both occluded and unoccluded trials as in REAT or MIRE. Simulated ear canal data were reported at NHCA earlier, demonstrating the frequency shift and magnitude parameters that reflect different earplug leak sizes. This paper reports on actual human testing with the LAT headphone system, with a comparison of LAT data for earplug fits with no leaks and different-sized leaks against REAT data for each of the same fits on the same subject. Strong positive correlation between LAT and low-frequency REAT results resulted, evidencing that the LAT system is predictive of REAT results for both well-fit and leaky earplugs. Given such objective data from a very quick occluded-only test, the hearing conservationist can quickly decide whether to re-fit or assign an alternative earplug, before proceeding to the more lengthy REAT or MIRE testing.

Learning Objectives:
1. Explain a new, novel acoustical test alternative to REAT- or MIRE-based Fit-Testing systems which saves considerable time in targeting poor earplug fit and associated leaks.
2. Describe the practice and utility of Fit-Testing systems for verification of individual fit of earplugs on individuals in the field setting.
3. Describe the difficulties with Fit-Testing systems as to test-retest reliability of REAT tests and instrumentation complexities of MIRE tests, time requirements, and other issues encountered in field testing.

Hearing protection devices (HPDs) play a critical role in mitigating noise-induced hearing loss in occupational settings. However, these devices often alter signals, hindering communication and localization abilities, particularly for workers with pre-existing hearing loss for which HPDs may attenuate key signals below their hearing thresholds. While hearing aids have shown promise in addressing similar issues in everyday noise, limited research exists on their efficacy in noisy industrial settings.
This study evaluates the performance of typical hearing aid algorithms implemented on a digital hearing protection device, specifically assessing their impact on speech intelligibility in industrial noise. Algorithms under investigation include wide dynamic range compression, linear amplification, compression limiting, noise reduction, and various combinations thereof. Using an adapted Hearing-in-Noise-Test, speech reception thresholds (SRTs) were measured in both industrial noise and quiet conditions for 10 participants with normal hearing and 24 participants with mild to moderate hearing loss. Participants also rated the comfort and quality of the speech signal for each algorithm configuration. This comparison of SRTs and subjective rating provides valuable insights into the effectiveness of various algorithms configurations. The findings will guide further research into optimizing digital HPDs for occupational environments, ultimately improving communication and safety for workers with hearing loss.

Learning Objectives:
1. Evaluate the effect of different hearing aid algorithms configuration on speech intelligibility in industrial noise in workers with or without hearing loss
2. Identify key hearing aid algorithms for use in industrial noise
3. Discuss applications of hearing aid technology in relation with hearing protection in occupational noise environments.

The ANSI/ASA S12.42-2010 standard can be used to estimate the attenuation for impulsive noises between 130 and 170 decibels peak sound pressure level (dB pSPL). The ANSI/ASA S12.42 method uses a complex transfer function between the signal received in the ear of an acoustic test fixture (ATF) and a reference transducer. The reference transducer is at the same radial distance from the impulse source and at less than 30 degrees from the ATF angle. The reference transducer is specified as a pencil-type pressure (> 40.6 cm long). The maximum angle and the minimum pencil probe dimensions could be incompatible near the source, or may introduce artifacts or hazards. In this study, several hearing protectors were evaluated with two rifles (A-Bolt .300 Winchester Magnum and Colt AR-15 5.56 caliber), two ATFs (GRAS 45CB) and five transducers (four ¼” microphones and one surface mount microphone). The ATFs were on opposite sides of the gun at distances for field levels between 180- and 140- dB pSPL. For each location and rifle, S12.42 metrics were calculated for all 20 combinations of ATF ear and reference transducer. Results indicated that S12.42 metrics were minimally affected by the locations of the reference transducers.

Learning Objectives:
1. Inform attendees about how tests of hearing protector attenuation using impulsive noise and acoustic test fixtures are performed.

2. Inform attendees about how the position of the test microphone might affect the evaluation of the impulse level dependent attenuation.

3. Inform attendees about the changes in impulse level dependent attenuation with impulse levels, impulse source, and protector type (earmuff and earplug).

While protection against high-level noise remains the primary purpose of hearing protection devices (HPDs), auditory situational awareness is also very important to maintain safety at work and to ensure acceptance to wear HPDs. One important factor is speech intelligibility in face-to-face communication, which may be impaired due to the HPD’s sound attenuation. To facility speech perception in conditions with temporarily lower noise levels, level-dependent HPDs offer acoustic transparency or even amplification of environmental sounds to prevent the users to take off their HPDs when attempting to communicate. To evaluate the benefits of such speech enhancing features, conducting formal listening tests is the gold standard. However, subjective testing is time-consuming and costly, and therefore instrumental metrics which accurately predict the outcome of such listening tests would be desirable. This study reviews recent advances in the development of such instrumental metrics and illustrates how they can be applied the context of HPDs. The focus is on level-dependent HPDs, which cannot be assessed using model approaches assuming linear audio signal processing. The contribution will illustrate application examples of benchmarking different HPDs, and demonstrate the potential of current models for real-time assessment of speech intelligibility in dynamically changing acoustic conditions.

Learning Objectives:
1. Describe the benefit and limitations of level-dependent hearing protectors with respect to speech intelligibility
2. Recall at least two ways to measure speech intelligibility and listening effort
3. Appraise the potential of novel instrumental metrics for speech intelligibility in the context of hearing protectors