In-ear noise dosimetry is a new, promising method of preventing noise-induced hearing loss (NIHL). Specifically, when in-ear noise dosimetry is used on a daily basis, a complete noise exposure history is established for an employee. With this in hand, the hearing conservationist can monitor exposures and intervene when necessary, taking whatever steps are required to prevent future overexposures. These steps can include changing protective devices, increasing wearing duration and improving fitting techniques. Since NIHL generally occurs after months and years of overexposures, the immediate intervention will prevent the hearing loss from progressing. Because the damage-risk criteria were developed using a sound level meter in open space, accurate in-ear measurements must compensate for the transfer function of the open ear (TFOE). This is challenging due to the variability of TFOE across the population and due to various microphone locations within the ear canal. A ‘generic’ TFOE can be used as an estimate for all users, or the TFOE can be measured on each employee by comparing an in-ear microphone measurement and a sound field microphone measurement of the same stimulus. These approaches will be discussed as fundamental elements of an industrial in-ear noise dosimetry program.

A Field-Microphone in Real Ear (F-MIRE) hearing protector Field Attenuation Estimation System (FAES) was developed for individual or group testing of any type or style of hearing protector device (HPD). Both occluded and unoccluded ear canal stimulus level measurements are made with a tiny Micro Electro-Mechanical System (MEMS) microphone mounted on a 2-mil thick flat flexible cable. The microphone is mounted inside of a conventional foam ear dam to protect the microphone and the ear canal and to facilitate insertion into the ear canal. The presence of the cable in the ear canal was demonstrated to have a negligible effect on attenuation measurements for both muff and insert-type HPDs. The system measures HPD attenuation in 1/1 or 1/3 octave bands and it is capable of simultaneously measuring HPD attenuation on up to eight human test subjects. Stimuli can be presented via headphones or loudspeakers. Human subject testing using both the laboratory based ANSI S12.6-2016 method and the F-MIRE system was performed using muff- and insert- type HPDs. Regression equations were generated from these data. These equations are incorporated in the F-MIRE software to allow valid comparisons between F-MIRE data and labeled HPD attenuation data.

At present exposure limits, one in four workers will develop a permanent hearing loss as a result of mining coal (Prince 1997). Mine Safety and Health Administration (MSHA) inspectors found in the period of 1986-1992 that approximately 25% of coal miners' daily noise doses exceeded MSHA's PEL. Virtually all mines have hearing conservation programs and virtually all miners are issued and told to wear either ear muffs or ear plugs. Nevertheless, miners still have a high rate of noise induced hearing loss (NIHL). An important question is to what degree the ineffectiveness of hearing conservation programs is due to failure of miners to wear muffs and plugs properly when they are needed and how much is due to inadequacies of hearing protectors. If the former is important, can technological innovations provide means to improve use of muffs and plugs. If the latter is important, can individual fit-testing improve noise reduction (NR) values achieved by miners. A related issue is whether fit-testing in an office environment adequately predicts NR values achieved during work if non-wearing times are excluded. To address those issues, WVU is conducting studies in a lab and in coal mines that primarily involve measuring sound levels in the ear (SPLear) concurrently with sound levels at the shoulder (SPLsh), allowing computation of NR values for protectors.

Researchers suggested that the individual fit test be conducted to estimate the protection effectiveness of workers’ hearing protection device (HPD) while working. Practically, it is convenient to conduct single, instead of multiple, fit test measurement. This study examined if a single trial of earplug fit test can represent multiple performances. Additionally, it investigated how much noise exposure was due to the miners’ failure to wear earplugs at work. A total of 11 subjects from 3 coal mines in West Virginia in 2009 were each repeatedly fit tested using the microphone-in-real-ear technique on their earplugs. For each miner values of noise reduction (NR) were determined. The same fit tested miners each wore the earplugs doing his normal full-shift work. The real-time noise doses were determined continuously using the two dosimeters, one at the shoulder and the other under the earplug for determining potential exposure dose and the dose the ear actually received. Most subjects’ noise reduction values varied over a range of more than 10 dBA, suggesting that subjects should be fit tested with multiple donnings. Failure to wear the earplug was an important factor in determining the miners’ noise exposure, accounting for 64.6% of their doses at ear on average and ranging from 33.3 to 93.4% across these subjects. Nearly half (45.5%) of the coal miners might not receive adequate protection with their earplugs. 35.2% of miners never wore any hearing protectors in the high noise environment and were in very high risk of hearing loss. Thus, an important portion of miners were exposed to excessive noise although the earplugs were provided.

Until recently, a standardized measurement procedure to determine peak insertion loss for hearing protectors was not available. This has led to confusion and uncertainty for hearing protector users who commonly use the devices in impulse noise, such as gunfire. Released in 2010, ANSI S12.42-2010 defines a test method and analysis procedure for measuring hearing protector impulse peak insertion loss. The required test fixture has recently become commercially available and laboratories are gaining experience making these measurements. Impulse peak insertion loss data will be presented for a variety of hearing protector types along with a description of the measurement procedure.

Background: Cardiac resynchronization therapy is rapidly emerging as an effective strategy for managing ventricular dysfunction and heart failure associated with congenital heart disease. Indications for therapy, optimal lead placement, and late outcomes are however lacking.Methods: We present three patients, one with Mustard procedure and two with congenitally corrected transposition of great arteries, who developed subpulmonic ventricular dysfunction 3-6 months after biventricular pacing +/- implantable cardioverter defibrillotor implantation, despite initial favorable result of resynchronization therapy. Possible factors for adverse outcome are relatively high pacing rate, unfavorable alteration of torsional contraction, and increased atrioventricular valve regurgitation due to suboptimal placement of larger diameter defibrillation leads.Results: Careful evaluation of patients, particularly indications for therapy, need to be rigorous; assessment of hemodynamic response at the time of implant and appropriate programming may improve the effectiveness of cardiac resynchronization therapy (CRT) in this patient population.Conclusion: Our case series emphasizes the need for a registry in the absence of randomized controlled trials, in order to identify patients who benefit most from CRT, and, importantly, recognize subgroups that respond poorly.

An apparatus adapted to be worn in an environment in which unsafe noise levels may be present for the purpose of continuously monitoring the noise level impinging upon the ear(s) of a user. The noise levels are monitored via a microphone housed within a hearing protective device, and located such that the noise level measured by the microphone is representative of the noise level impinging upon the ear(s) of the user when the hearing protective device is being worn in either a primary or secondary position. The noise level is recorded along with its duration to calculate a cumulative noise dose for an individual user, and to warn the user of when the noise dose exceeds a preset level. The apparatus further provides for a means of transmitting the noise level and dose information to a data storage/retrieval device such as a PC for maintaining a history of noise exposure for the individual user of the device. A method of using an apparatus as described, or a similar device, to continuously monitor an individual's noise exposure is also disclosed.

Commonly, attenuation and comfort are the major criteria used in selecting a hearing protective device (HPD) for a given noise environment. The objective of this study was to develop a method of HPD selection in which speech intelligibility is introduced as an additional selection parameter. Subjects with normal hearing, mild hearing loss due to noise exposure, and severe hearing loss due to noise exposure listened to speech presented in a background of noise. Both the speech and noise were filtered to emulate the transfer function of either an average plug type or an average muff type HPD, and the resulting signal was presented to the listener via headphones. Three noises with spectra of high-, middle-, and low-frequency energy concentration, respectively, were used, making for a total of six tested conditions. For each condition, six presentation levels were tested, simulating various degrees of HPD attenuation. A HPD selection criteria was developed based on the word recognition scores for each condition. This criteria was tested using actual haring protectors in a free-field environment, and a comparison with the results from the simulation was made.

The most common procedure for selecting hearing protective devices (HPDs) is the Noise Reduction Rating (NRR). The NRR can be misleading and often results in the selection of HPDs that either under- or over-protect the wearer. The wearer of an under-protective HPD is likely to experience noise-induced hearing loss. The use of over-protective HPDs can needlessly reduce speech communication, the ability to hear warning signals, and the ability to recognize important machine sounds. Workers fit with over-protective HPDs are also less likely to properly wear their HPDs. An articulation index (AI) based method of ranking HPDs for use in specific noise exposures was developed in conjunction with the American Iron and Steel Institute (AISI). The calculations used in the procedure incorporate the attenuation characteristics of the HPD, the spectrum of the noise source, the hearing thresholds of the wearer, the nonlinear growth of masking, and the predicted level of speech in noise. The HPD rankings are intended to insure that adequate attenuation and optimum communication ability is achieved.

The attenuation provided by a sample of circumaural hearing protectors (ear muffs) was measured using the physical ear attenuation test (PEAT). The PEAT utilized a small electret microphone mounted in a silicon ear plug in the outer ear of a human subject. The subjects were exposed to a high level (about 100 dBA) of pink noise with and without the hearing protector fitted. The attenuation provided by the protector was calculated by subtracting the spectrum measured under the protector from the spectrum measured without the protector. The results of the PEAT evaluation were compared to the results obtained using the test method described in ANSI Standard S12.6-1984, the Method for the Measurement of the Real-Ear Attenuation of Hearing Protectors. Agreement was found between the methods for the test frequencies from 250 to 8000 Hz. The PEAT results at 125 Hz were lower than the results obtained with the ANSI S12.6-1984 method.

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