2025 NHCA Annual Conference

Music Audiology is a small speciality, however music people (performers, engineers, industry support professionals, avid concert goers) are a large population who seek hearing services from all practitioners. In this session, many of the most active and prolific speakers, clinicians, and researchers in the field will share important updates to best practice and technology/procedure updates pertinent to anyone interested in this population. Specific topics of focus will include recent progress in teleaudiology, best practices for safe use of in-ear monitors, verification and demystification of custom filtered hearing protection for performers, and updates on the many global initiatives for hearing loss prevention.

Learning Objectives:
1.Apply clinical best practices to the audiologic care of musicians and music industry professionals.
2.Identify tools and methods available to verify hearing protection devices and in-ear monitors.
3.Assess how teleaudiology impacts access to and provision of hearing healthcare to music industry professionals.

Music Audiology is a small speciality, however music people (performers, engineers, industry support professionals, avid concert goers) are a large population who seek hearing services from all practitioners. In this session, many of the most active and prolific speakers, clinicians, and researchers in the field will share important updates to best practice and technology/procedure updates pertinent to anyone interested in this population. Specific topics of focus will include recent progress in teleaudiology, best practices for safe use of in-ear monitors, verification and demystification of custom filtered hearing protection for performers, and updates on the many global initiatives for hearing loss prevention.

Learning Objectives:
1.Apply clinical best practices to the audiologic care of musicians and music industry professionals.
2.Identify tools and methods available to verify hearing protection devices and in-ear monitors.
3.Assess how teleaudiology impacts access to and provision of hearing healthcare to music industry professionals.

Impulsive noise and blast are known to cause auditory deficits, but the relationship between exposure and injury is not well quantified. To better understand military-specific auditory injuries, Walter Reed National Military Medical Center (WRNMMC), in partnership with the Defense Center for Public Health Aberdeen (DCPH-A) and other collaborators within the DOD, has been engaged in a multiyear effort to characterize the hearing changes that occur following exposure to high-level impulsive noise.

This work has been enabled by two major advances: the development of wearable dosimeters capable of measuring both impulsive and continuous noise, and the development of boothless audiometer systems capable of measuring pre- and post-exposure hearing performance under field conditions. These technologies have made it possible to measure cumulative noise exposures and the resulting hearing changes in hundreds of service members who have been engaged in training events with heavy weapons and other high-level impulsive noise sources. The results provide insights into the development of improved hearing risk criteria for impulsive noise.

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 the U.S. Government.

Learning Objectives:
1. Describe the technological advancements in wearable dosimeters and boothless audiometers that have enabled the measurement of hearing changes in military personnel.
2. Explain the importance of measuring temporary threshold shifts in hearing.
3. Apply prospective data into the development of improved hearing risk criteria for impulsive noise.

Hearing protection devices are limited in their ability to attenuate high-level firearm impulse noise. Hazardous sound levels can reach the cochlea via the flanking bone/tissue conduction pathway. Assessing bone/tissue’s role in high-level impulse transduction could allow for more accurate assessment of risk to hearing and other body systems (i.e. brain health). The aim of this study was to estimate firearm sound levels conducted via the bone/tissue pathway using temporal bone acceleration recordings from an anatomic head simulator. Firearm impulses from two different rifles were recorded using an anatomic head simulator instrumented with bilateral triaxial accelerometers in the temporal bone region, high level pressure measurement microphones within each ear canal, and a hydrophone and angular rate sensor located near the center of the head. Field levels of the firearm impulses were determined using recordings from a measurement microphone positioned near the head simulator. Firearm impulse-related acceleration was converted to equivalent sound pressure using previously published Reference Equivalent Threshold Acceleration Levels and then compared with recordings made in the sound field. Results indicated that bone/tissue conducted sound levels estimated using this method corresponded with published bone conduction attenuation limits for .5, 1 and 2 kHz frequency bands.

Learning Objectives:
1. Describe the role of the bone/tissue conduction pathway for high-level impulse sounds.
2. Explain firearm impulse sounds can generate substantial head acceleration.
3. List advantages and disadvantages of using acceleration of an anatomical head simulator to estimate sound levels conducted via the bone/tissue pathway.

Impulsive noise is generated by the rapid release of compressed gases (impulse) or by the collision of solid objects (impact) and is most common in metalworking, construction, shipyard, and mining industries as well as law enforcement and the military. Research on the effect of complex (mixed steady state and impulsive) noise on hearing health suggests it may be more damaging than an equal amount of energy from steady state noise. There is also concern that repetitive low-level blast exposures might result in chronic brain health problems. Unfortunately, no commercial noise dosimeter currently measures complex noise accurately. We report on the collaborative development of a dual-microphone noise dosimeter with a wide dynamic range of 40 dBA up to 185 dB Peak with a sampling rate of up to 96 kHz. Real-time processing accounts for both steady-state and impulses into the calculation of total noise dose, records individual impulses that exceed a pre-specified threshold, and counts the number of impulses. We present data obtained in the laboratory with comparison to reference equipment, as well as in field settings, including military weapons training. We conclude on the utility of the device and future development needed to integrate it into occupational health programs.

Learning Objectives:
1. Distinguish the difference between steady-state noise, impulsive noise and complex noise.
2. Describe what makes impulse noise difficult to measure accurately.
3. Recognize the metrics that can be used to report measurements of noise that may include impulsive events.

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.