Acoustic exposure to high intensity and/or prolonged noise causes temporary or permanent threshold shifts in auditory perception, reflected by reversible or irreversible damage in the cochlea. Aminoglycoside antibiotics, used for treating or preventing life-threatening bacterial infections, also induce cytotoxicity in the cochlea. Combined noise and aminoglycoside exposure, particularly in neonatal intensive care units, can lead to auditory threshold shifts greater than simple summation of the two insults. The synergistic toxicity of acoustic exposure and aminoglycoside antibiotics is not limited to simultaneous exposures. Prior acoustic insult which does not result in permanent threshold shifts potentiates aminoglycoside ototoxicity. In addition, exposure to subdamaging doses of aminoglycosides aggravates noise-induced cochlear damage. The mechanisms by which aminoglycosides cause auditory dysfunction are still being unraveled, but likely include the following: 1) penetration into the endolymphatic fluid of the scala media, 2) permeation of nonselective cation channels on the apical surface of hair cells, and 3) generation of toxic reactive oxygen species and interference with other cellular pathways. Here we discuss the effect of combined noise and aminoglycoside exposure to identify pivotal synergistic events that can potentiate ototoxicity, in addition to a current understanding of aminoglycoside trafficking within the cochlea. Preventing the ototoxic synergy of noise and aminoglycosides is best achieved by using non-ototoxic bactericidal drugs, and by attenuating perceived noise intensity when life-saving aminoglycoside therapy is required.

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Currently, there are more than 445,000 veterans receiving compensation for hearing loss associated with military service, and 395,000 receiving compensation for service-related tinnitus. In addition to compensation payments, service-related hearing disorders cost the US Department of Veterans Affairs in terms of provision of hearing aids, hearing aid-related services, and clinical services at its 220 facilities nationwide. It is imperative that hearing conservation among military personnel and veterans be addressed. In this paper, we describe the rationale for and the development of a multimedia Hearing Loss Prevention Program aimed at preventing the progression of hearing loss among veterans associated with social, recreational, and nonmilitary occupational noise exposure. The program was developed based on the principles outlined in the Health Belief Model of Rosenstock (1966) and the Health Promotion Model of Pender et al. (2002).

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It has been twenty-five years since the final version of the Hearing Conservation Amendment was issued by the Occupational Safety and Health Administration in the U.S. Department of Labor. Since that time, some things have changed and others have stayed exactly the same. Certainly the noise-exposed workforce is more knowledgeable about the hazards of noise, and the use of hearing protection devices (HPDs) has greatly increased. There have been significant strides in the technology for measuring noise and for protecting hearing through HPDs. But there is considerable room for improvement. Some of the noise regulation's provisions are embarrassingly outdated, some are in dire need of improvement, and others, such as the requirements for engineering noise control, are not being enforced. Sadly, there seems to be little progress in reducing overall noise exposure levels. What needs to be done at this point is a major overhaul of the noise regulation: recommitment to engineering noise control; reduction of the permissible exposure limit (PEL) to 85 dBA; a shift to the 3-dBA exchange rate; and a nationwide assessment of hearing loss in American workers to determine the effectiveness of current hearing conservation measures to identify and address the weaknesses in programs and regulations.

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Operational hearing protection and maintenance of audibility of signals and speech are considered force multipliers in military operations, increasing Soldier survivability and lethality. The in-field research described in this paper was conducted to examine operational performance effects of three different hearing enhancement protection systems (HEPS) that are intended to provide both protection and audibility. The experiment utilized operationally-defined measures in full-scale, simulated combat scenarios with Army ROTC Cadet Soldiers as subjects. The Soldiers' operational performance was evaluated in two missions: reconnaissance and raid (attack on enemy camp). Both missions had substantial hearing requirements, including communications, signal detection/recognition, and distance judgments. Operational performance was measured by objective metrics of Squad performance, including the distances required to detect an enemy insurgent camp under each HEPS, and by subjective metrics, such as the Army's dimensions of combat-related mission success as evaluated by Army Officers who served as training leaders/observers. Other subjective ratings were obtained after each training exercise from both the Officers and the Soldiers, including detailed impressions about each HEPS after extended use. Two of the three HEPS were electronic sound transmission devices (comprising an ambient sound pass-through filtering and amplification circuit): a Peltor Comtac II circumaural headset (NRR=21; 16 dB maximum gain); and a Communications Enhancement Protection System (CEPS) (NRR=29; 36 dB maximum gain). One passive, level-dependent HEPS was used, the yellow end of the Combat Arms Earplug, which provides amplitude-sensitive attenuation that sharply increases when the ambient sound is above about 110 dB (e.g., due to a gunshot), but which provides an NRR of 0 and very little attenuation below 1000 Hz in lower ambient noise levels. In the military mission entailing location of and attack on an enemy camp, the CEPS device resulted in the longest (earliest) average auditory detection distance of the camp (400 feet), followed by the Peltor (233 feet) and then the Combat Arms Earplug (150 feet), in comparison to detection by the unprotected, normal ear at about 220 feet. Commanding officers' ratings of mission performance and overall success slightly favored the electronic HEPS, but these ratings were dependent upon the particular mission undertaken. Ergonomics and usability issues abounded with the electronic HEPS, and the Soldiers' subjective ratings showed variability across all three devices, with device preference depending upon the particular dimension being rated (e.g., comfort vs. hearing ability). Clearly, the results of this in-field experiment demonstrate that more development is needed to achieve the levels of hearing performance and user acceptance from the HEPS that is desirable and needed for combat conditions. In this vein, it is important to note that HEPS designs are continually evolving, and certain upgrades to the three devices evaluated in the late 2006 timeframe of this study have occurred and further evaluations are thus warranted.

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Exposure to loud sounds is a common cause and exacerbater of tinnitus - a troubling auditory symptom that affects millions of people worldwide. Clinical research at the National Center for Rehabilitative Auditory Research has resulted in a clinical model of tinnitus management referred to as Progressive Audiologic Tinnitus Management (PATM). The model involves five hierarchical levels of management: Triage, Audiologic Evaluation, Group Education, Tinnitus Evaluation, and Individualized Management. Counseling by audiologists and, as needed, mental health providers, is a key component of PATM. This style of counseling focuses less on didactic informational counseling; instead, counseling is used for facilitating patients' learning to adjust to the disturbing auditory symptom by successfully employing tools from two powerful skillsets for self-management of chronic tinnitus - the therapeutic uses of sound and techniques from cognitive-behavioral psychology. This article provides an overview of the methods of counseling used with PATM and provides details concerning the overarching principles of collaborative adult learning that are believed to be most important in facilitating self-management by patients who complain of tinnitus.

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The effectiveness of a hearing loss prevention program within a college may be dependent on attitudes among students majoring in music. The purpose of this study was to assess the attitudes of music majors toward noise and to compare them to students not majoring in music. Participants ( N = 467) filled out a questionnaire designed to assess attitudes toward noise in youth culture and attitudes toward influencing their sound environment. Results showed that students majoring in music have a healthier attitude toward sound compared to students not majoring in music. Findings also showed that music majors are more aware and attentive to noise in general, likely to perceive sound that may be risky to hearing as something negative, and are more likely to carry out behaviors to decrease personal exposure to loud sounds. Due to these differences, music majors may be more likely than other students to respond to and benefit from a hearing loss prevention program.

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Exposure to high-intensity impulse noise from the recreational use of firearms is a common cause of noise-induced hearing loss (NIHL). Although recreational firearm users who shoot firearms without proper hearing protection are at risk for NIHL, a specific subgroup involved in hunting waterfowl may also be at risk due to their particular shooting habits. The goal of the present study was to investigate the shooting habits of this particular group of U.S. recreational firearm users. A 23-item written survey was sent to waterfowl hunting club members regarding their shooting behaviors, use of hearing protective devices (HPDs), and auditory status. Results indicated that waterfowl hunters in this study typically used large bore semiautomatic shotguns, did not consistently utilize HPDs during target practice or hunting and were exposed to multiple, unprotected shots during the past waterfowl season. Most subjects reported hunting in reverberant acoustic environments (hunting blinds). This group of recreational firearm users also reported high incidences of hearing loss and tinnitus. Information provided by this study may help hearing conservationists and hearing healthcare providers understand and better educate these shooters regarding the risk of acquiring NIHL.

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Clinical audiologists and audiometric equipment manufacturers have embraced the clinical use of insert earphones; however, their use in audiometric testing in occupational hearing loss prevention programs has been limited. This study was undertaken to research whether certified audiometric technicians without practical hands-on training could reliably use insert earphones when compared to a clinically experienced audiologist. Hearing thresholds were obtained on 60 human ears by six certified audiometric technicians using insert earphones for the first time. Technician-acquired audiometric thresholds were compared to thresholds obtained under the same conditions by a clinical audiologist experienced in the use of the insert earphones. Statistical analyses of audiometric thresholds were performed to investigate the relationships between audiometric threshold values at each frequency obtained by certified technicians vs. the audiologist. These relationships were examined for the group as a whole as well as when ear tip size and earphone insertion depth varied between the audiologist and the technicians. No significant differences (p > .01) were found between mean group thresholds at any of the test frequencies (500-8000 Hz). Mean group thresholds differed by <1.2 dB. Pearson Product-Moment correlation (PPMC) coefficients suggested that thresholds obtained by the audiometric technician were highly correlated with those obtained by the audiologist. There were no significant threshold differences (p > .01) even when the audiologist and technicians varied in their selection of ear tip size or in the amount of insertion depth achieved. This study suggests that CAOHC-certified audiometric technicians can reliably use insert earphones without practical training when testing in quiet environments by reading the earphone package directions provided by the manufacturer.

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The purposes of the study were to investigate children's knowledge about hearing conservation, the types of protective behaviors they would adopt in noise, the agreement between children's knowledge and intended behaviors in hearing protection, and reasons why they would not take any protective action in noise. A questionnaire was administered to 479 fourth and fifth graders in their school classrooms. Results indicated that children scored low (62.0%) on this hearing conservation questionnaire. They scored the highest in strategies of hearing protection (69.9%), followed by their knowledge in general hearing health (62.6%) and noise hazards (49.6%). Only 55% of children knew that hearing protective devices could protect them against noise. Approximately 28% of children did not intend to adopt any protective behavior in noise and the major reason for this was lack of knowledge. Children's knowledge and their noise protective behavior were correlated ( P < .05). However, possessing knowledge did not guarantee that children would adopt such behaviors when they were exposed to loud sounds. It is important to increase children's knowledge about hearing protection and hazardous noise as well as to encourage actual protective actions.

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