Human exposures and their associated hearing loss profiles: Music industry professionals.

Music industry professionals represent a vulnerable population to music induced hearing disorders (MIHDs). In addition to the impacts that the development of hearing disorders secondary to noise exposure can have on quality of life and communication, MIHDs can impact the afflicted individual's professional performance, and in turn employability. Within the music industry there are individual and institutional barriers to traditional hearing conservation interventions. Pharmaceutical interventions for hearing loss could potentially address some of these barriers, yet there are significant considerations and cautions which should be addressed.

Validation of clinical techniques for verification of uniform attenuation earplugs.

OBJECTIVE: Uniform attenuation earplugs (UAE) theoretically provide near even attenuation across frequencies when built to a manufacturer's specifications. Unfortunately, there is no current research available confirming if custom-molded uniform attenuation earplugs (UAE) are made to specifications nor is there guidance available on clinical methods of measuring attenuation of uniform attenuation earplug (UAE) devices. The goal of this study was to evaluate different procedures for UAE verification and to determine the most accurate clinically accessible verification protocol. DESIGN: Attenuation was measured using probe microphone techniques, as well as real-ear attenuation at threshold (REAT) measurements under circumaural earphones, soundfield speakers and supra-aural earphones. Comparisons were made to a reference system created in the laboratory. STUDY SAMPLE: Seventeen adult participants, totaling 30 ears. RESULTS: The results of this study demonstrate that the REAT measured in the soundfield using a narrowband noise stimulus with masking in the contralateral ear is currently the most accurate and widely available method of verifying UAEs. CONCLUSIONS: Factoring in clinical efficiency, the authors of this study recommend verifying attenuation levels using a soundfield REAT procedure as best clinical practice. In addition, the data suggests that REAT measurements under circumaural earphones are an acceptable second choice method.

Sudden Bilateral Hearing Loss, Tinnitus, and Vertigo as Presenting Symptoms of Chronic Myeloid Leukemia.

OBJECTIVES: The objective was to describe a unique case of sudden bilateral hearing loss, tinnitus, and vertigo presenting as the first symptoms of chronic myeloid leukemia (CML). METHODS: A patient case is discussed along with a review of associated literature. RESULTS: A patient presented with sudden onset hearing loss, tinnitus, and vertigo, and was diagnosed with CML with an initial white blood cell (WBC) count of 555 000 per microliter. The proposed etiology of otologic symptoms is hyperleukocytosis. Serial audiograms showed minimal improvement in hearing despite reduction of WBC. CONCLUSION: In cases of bilateral, sudden onset sensorineural hearing loss, evaluation for systemic causes of otologic symptoms, including CML, should be considered.

Safe Use of Acoustic Vestibular-Evoked Myogenic Potential Stimuli: Protocol and Patient-Specific Considerations.

BACKGROUND: Vestibular-evoked myogenic potentials (VEMPs) are commonly used clinical assessments for patients with complaints of dizziness. However, relatively high air-conducted stimuli are required to elicit the VEMP, and ultimately may compromise safe noise exposure limits. Recently, research has reported the potential for noise-induced hearing loss (NIHL) from VEMP stimulus exposure through studies of reduced otoacoustic emission levels after VEMP testing, as well as a recent case study showing permanent sensorineural hearing loss associated with VEMP exposure. PURPOSE: The purpose of this report is to review the potential for hazardous noise exposure from VEMP stimuli and to suggest clinical parameters for safe VEMP testing. RESEARCH DESIGN: Literature review with presentation of clinical guidelines and a clinical tool for estimating noise exposure. RESULTS: The literature surrounding VEMP stimulus-induced hearing loss is reviewed, including several cases of overexposure. The article then presents a clinical calculation tool for the estimation of a patient's safe noise exposure from VEMP stimuli, considering stimulus parameters, and includes a discussion of how varying stimulus parameters affect a patient's noise exposure. Finally, recommendations are provided for recognizing and managing specific patient populations who may be at higher risk for NIHL from VEMP stimulus exposure. A sample protocol is provided that allows for safe noise exposure. CONCLUSIONS: VEMP stimuli have the potential to cause NIHL due to high sound exposure levels. However, with proper safety protocols in place, clinicians may reduce or eliminate this risk to their patients. Use of the tools provided, including the noise exposure calculation tool and sample protocols, may help clinicians to understand and ensure safe use of VEMP stimuli.

Time-Varying Distortions of Binaural Information by Bilateral Hearing Aids: Effects of Nonlinear Frequency Compression.

In patients with bilateral hearing loss, the use of two hearing aids (HAs) offers the potential to restore the benefits of binaural hearing, including sound source localization and segregation. However, existing evidence suggests that bilateral HA users' access to binaural information, namely interaural time and level differences (ITDs and ILDs), can be compromised by device processing. Our objective was to characterize the nature and magnitude of binaural distortions caused by modern digital behind-the-ear HAs using a variety of stimuli and HA program settings. Of particular interest was a common frequency-lowering algorithm known as nonlinear frequency compression, which has not previously been assessed for its effects on binaural information. A binaural beamforming algorithm was also assessed. Wide dynamic range compression was enabled in all programs. HAs were placed on a binaural manikin, and stimuli were presented from an arc of loudspeakers inside an anechoic chamber. Stimuli were broadband noise bursts, 10-Hz sinusoidally amplitude-modulated noise bursts, or consonant-vowel-consonant speech tokens. Binaural information was analyzed in terms of ITDs, ILDs, and interaural coherence, both for whole stimuli and in a time-varying sense (i.e., within a running temporal window) across four different frequency bands (1, 2, 4, and 6 kHz). Key findings were: (a) Nonlinear frequency compression caused distortions of high-frequency envelope ITDs and significantly reduced interaural coherence. (b) For modulated stimuli, all programs caused time-varying distortion of ILDs. (c) HAs altered the relationship between ITDs and ILDs, introducing large ITD-ILD conflicts in some cases. Potential perceptual consequences of measured distortions are discussed.

Sudden Bilateral Hearing Loss After Cervical and Ocular Vestibular Evoked Myogenic Potentials.

OBJECTIVE: Cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs) are commonly used in evaluation of neurotologic disorders. We present a case of sudden bilateral hearing loss immediately after oVEMP and cVEMP testing. The hearing loss did not recover. To our knowledge, no previous case reports discuss sudden hearing loss, especially bilateral, associated with VEMP testing. PATIENT: A single patient with sudden bilateral hearing loss that has persisted after cVEMP and oVEMP. INTERVENTION: The patient had a history of chronic daily dizziness. She underwent vestibular function testing that included cVEMP and oVEMP testing. A significant bilateral sensorineural hearing loss was noted immediately after cVEMP and oVEMP testing and confirmed with audiometric testing. Despite the use of oral steroids, her hearing loss did not recover. MAIN OUTCOME MEASURES: Serial audiograms, calculated maximum total sound energies to each ear. RESULTS: Pre-VEMP versus post-VEMP audiograms show increased thresholds and decreased word recognition scores; total sound energy delivered to each ear shows significant sound exposure. CONCLUSION: Although VEMP testing is thought to be safe and well tolerated, a significant amount of sound can be delivered to the cochlea, and certain individuals may be susceptible to acoustic trauma at these levels. We recommend limits for VEMP stimuli levels and attention to total sound exposure when multiple trials are used.

Teenage use of portable listening devices: a hazard to hearing?

BACKGROUND: Recently, a number of popular media articles have raised some concern that portable listening devices (PLDs) may be increasing the risk for music-induced hearing loss (MIHL). However, literature regarding adolescents' listening behavior and how their attitudes and beliefs relate to behavior is currently limited. PURPOSE: The purposes of this study were (1) to investigate the relationship between volume control settings and output levels of PLDs, (2) to examine how adolescents' listening behavior changes as a function of background noise and noise isolation, (3) to investigate the relationship between self-reported listening levels and laboratory-measured listening levels, and (4) to evaluate the validity of the Listening Habits Questionnaire as a research tool for evaluating how attitudes and beliefs relate to PLD use behavior. RESEARCH DESIGN: A descriptive study. Experiment 1 evaluated the output levels of a set of PLDs, and Experiment 2 characterized the listening behavior and attitudes toward PLD use of a group of adolescents. STUDY SAMPLE: Twenty-nine adolescents aged 13-17 yr, with normal hearing, participated in Experiment 2. DATA COLLECTION AND ANALYSIS: Experiment 1 evaluated the output levels of a set of PLDs with stock and accessory earphones using an acoustic manikin. Experiment 2 included survey measures of listening behavior and attitudes as well as output levels measured using a probe microphone. CONCLUSIONS: The output levels of PLDs are capable of reaching levels that could increase the risk for MIHL, and 14% of teenagers in this study reported behavior that puts them at increased risk for hearing loss. However, measured listening levels in the laboratory settings did not correlate well with self-reported typical listening levels. Further, the Listening Habits Questionnaire described in this study may provide a useful research tool for examining the relationship between attitudes and beliefs and listening behavior.