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PubMed1977

[A protective hearing aid (author's transl)].

A device consisting of a hearing protector headset and a modified hearing aid is used as a protective hearing aid for normal hearing subjects. Understanding of sufficiently redundant speech is remarkably improved, especially for noise level of about 20 dB above speech level. Tests have been made with the "Freiburger Zahlentest" and amplified "party noise" up to noise levels of 105 dBSPL. As an example: the above mentioned device enables the wearer to understand speech of 85 dB with 105 dB loud speech similar background noise while still the ears are charged with no more than 90 dB at all. Application for hyperacusis and recruitment patients is discussed.

Audiovisual Aids↗
PubMed1996

Evaluation of muff-type hearing protectors as used in a working environment.

Studies evaluated muff-type hearing protection devices (HPDs) in a mining environment. Noise reduction measurements were made using miniature microphones inside and outside the HPD cup. Laboratory tests conducted prior to field evaluations indicated that the results of this physical method were similar to the results of the American National Standards Institute (ANSI) real-ear-attenuation-at-threshold method. A total of 23 models of HPDs and 545 machines (20 different machine types) were evaluated in the field phase, resulting in 1265 HPD evaluations. The effectiveness of each HPD model in terms of dBA noise reduction is presented as a function of the metric (C-A), which characterizes the spectrum of the machine noise. The dBA reductions for various combinations of HPD models and machine types are also presented. The results show that the field performance of muff-type HPDs is significantly less than that specified by the Environmental Protection Agency Noise Reduction Rating (NRR), especially for low-frequency noise sources such as internal combustion engines. Thirty-two percent of the operators of such machines observed noise reductions of 10 dBA or less. Across all machine types, 20% of the workers realized an observed noise reduction of 10 dBA or less. It is concluded that the NRR grossly overestimates HPD performance. In addition, the NRR is not a good indicator for comparing HPD models since in many instances HPDs with lower NRRs out-performed those with higher NRRs. The laboratory-derived NRRs' failure to predict the HPD field performance was related primarily to the inaccuracy of the basic laboratory attenuation data from which the NRRs were computed, and to a lesser extent to shortcomings in the NRR computational procedure.

Ear Protective Devices↗
PubMed1993

Evaluation of an earphone-support device for measuring earplug attenuation.

A new procedure for determining the attenuation of earplugs with a standard audiometric headset was evaluated. The procedure utilized a device that supports a conventional supraaural earphone cushion (MX-41/AR) such that it does not contact the pinna or the earplug during threshold measurement. The attenuation provided by a foam earplug was estimated on a group of normal-hearing subjects using this method. The resulting attenuation values were compared to data obtained using sound field (ANSI S12.6-1984) methods, and to values obtained by simply placing the earphone on the pinna. Results suggest that the test re-test reliabilities of both the earphone-support method and the earphone-only method were comparable to that of the sound field procedure. Also, of the four test frequencies employed (1, 2, 3 and 4 kHz), the closet correspondence between attenuation estimates obtained using the ANSI procedures and estimates obtained with the support device occurred at 1 and 2 kHz.

Adolescent↗
PubMedDate not supplied

Factors affecting the use of hearing protectors among classical music players.

Classical musicians are often exposed to sound levels that exceed the Finnish national action limit value of 85 dB(A). Still, the use of hearing protectors is uncommon among musicians. The purpose of this study was to find out musician's attitudes towards hearing protectors, and under which conditions hearing protectors are used. The study group consisted of five major classical orchestras in the Helsinki region. The players were asked to fill out a questionnaire with questions on hearing protection, ear symptoms, including tinnitus, hearing loss, pain in the ears, and temporary ringing in the ears. Also, questions concerning stress and working environments were asked. Of those who responded, 94% were concerned about their hearing to some degree. Only 6% of the musicians always used hearing protector devices (HPDs). Self-reported hearing loss was quite common, with 31% of the musicians reporting some hearing loss. Temporary tinnitus was even more common at 37%. There were 15% of women, and 18% of men reporting permanent tinnitus. Hyper-acousis was reported by 43% of the musicians. The ear symptoms affected the usage rate. Hearing protectors were used more often among musicians having ear symptoms (20%) than those reporting no symptoms (6%). Further, the 43% of the musicians found their work to be interesting and meaningful. Stress was experienced to some extent by 60%, and musicians with ear symptoms had three to nine times more stress and felt their working environment noisier. The study shows that musicians seldom use hearing protectors before symptoms begin. Symptoms increased usage rate, but the usage levels are still far from ideal. Motivation and training is needed to improve hearing protector use among musicians.

Attitude↗
PubMed1997

Environmental awareness and level-dependent hearing protection devices.

OBJECTIVE: The effect of level-dependent hearing protection devices (HPDs) on subjects' ability to identify real-life environmental sounds was investigated. DESIGN: Eighteen subjects with no hunting experience attempted to identify sounds (crow, duck, turkey, deer, owl, goose, and person) recorded at various distances in the presence of the SoundScope and Sonic II level-dependent HPDs as well as in an open ear condition. Knowles Electronic's Manikin for Auditory Research was employed in making the experimental recordings. The Sonic II accomplishes level-dependent attenuation via a passive mechanism, whereas the SoundScope employs active circuitry that attenuates loud sounds while providing a small amount of high frequency amplification for soft sounds. Both devices are commercially available and are advertised for hunters/shooters. Sound identification scores (SISs) were determined for each condition. RESULTS: Mean SISs differed significantly among the three earplug conditions, collapsed over type of sound and distance, with the best SIS obtained under the open ear condition (96.43%) and the worst under the Sonic II condition (84.13%). Further analysis revealed that the listening conditions differed significantly only at the 100 yard distance. CONCLUSIONS: Auditory awareness was not maintained by either device investigated during the 100 yard condition. However, auditory awareness was maintained by both devices at a distance of 75 yards or closer. These devices may be appropriate for use in certain hunting/shooting situations depending on several factors including type of game being hunted, environment, and shooting range of the weapon. Further support also is provided for the usage of level-dependent HPDs during recreational shooting activities (i.e., at a shooting range).

Adolescent↗
PubMed1997

Comparison between subjective and objective measures of active hearing protector and communication headset attenuation.

A masked-threshold and a loudness-balance method have been developed to estimate the attenuation of communication headsets and hearing protectors with built-in active noise reduction (ANR) systems. Both methods are used to estimate the attenuation of the ANR systems and the masked-threshold method is also used to estimate the total attenuation (active plus passive) of the device. The procedures are designed to be used in the presence of environmental noise, and to minimize the noise exposure of subjects during the measurements. For comparison, physical measurements of insertion loss have also been performed using a miniature microphone in the concha. Experiments showed that the masked-threshold methods tends to give increased estimates of the attenuation if the noise reduction of the left and right earcup ANR systems differs, as commonly occurs in practice. In contrast, the loudness-balance method reduces the estimates of the active attenuation. Insertion loss measurements may be influenced by the position of the microphone, owing to the spatial variability of the sound field under an earmuff when the ANR system is operating. Differences between physical and subjective measurements of up to 20 dB have been obtained in this study at frequencies of 250 Hz and below for a device in which the sound pressure varied substantially near, and within, the ear canal.

Adult↗
PubMed1984

Earplugs--a computer program for simulation of personal hearing protection devices.

Earplugs is a program to allow predictive evaluation of earplugs and earmuffs. Written in Basic for the Apple II+, it is translatable into all other versions of Basic. The program allows the user to compare the attenuation capabilities of any earplug versus the environmental octave band analysis for the workplace in question. This version of the program provides a plot of the results.

Ear Protective Devices↗
PubMed1985

Is real-ear attenuation at threshold a function of hearing level?

In the course of measuring the real-ear attenuation at threshold (REAT) of experimenter-inserted E-A-R foam earplugs on 100 subjects, a statistically significant correlation was observed between attenuation and hearing level (for normal listeners, HTL less than or equal to 20 dB) at test frequencies from 2-8 kHz. Listeners with more sensitive hearing obtained better protection. The relationship was most robust at 6 and 8 kHz. For hearing levels greater than 20 dB, attenuation appeared independent of hearing level. A hypothesis was developed to explain the relationship for the normal listeners, based upon the fact that the high-frequency attenuation of the earplug was nearly bone-conduction limited. The hypothesis suggested that the attenuation of a hearing protector that provided substantially lower protection would not exhibit the same relationship. Data for such a device were collected for 70 subjects, and indeed demonstrated reduced correlation between attenuation and hearing level. Implications of the results of the experiments are discussed with regard to hearing level requirements for hearing protector attenuation test subjects, utilization of hearing-impaired listeners to measure REAT at suprathreshold (with respect to normal listeners) sound pressure levels, and linearity of hearing protector attenuation as a function of sound level.

Acoustics↗
PubMed1989

An acoustic head simulator for hearing protector evaluation. I: Design and construction.

As an alternative to subjective methods, an acoustic head simulator was constructed for hearing protector evaluation. The primary purpose of the device is for hearing protector testing and research under high-level steady-state and impulse noise environments. The design is based on the KEMAR manikin and therefore approximates the physical dimensions and the acoustical eardrum impedance of the median human adult. The head simulator includes a mechanical reproduction of the human circumaural and intraaural tissues with a silicone rubber material. A compliant head-neck system was constructed to approximate the vibrational characteristics of the human head in a sound field in order to simulate the inertia effect of earmuffs. The bone-conducted sounds are not mechanically reproduced in the design. Applications for the device are reported in a companion article [C. Giguère and H. Kunov, J. Acoust. Soc. Am. 85, 1197-1205 (1989)].

Auditory Threshold↗
PubMedDate not supplied

Explaining Mexican American workers' hearing protection use with the health promotion model.

BACKGROUND: Mexican American workers are vulnerable to noise-induced hearing loss, the most common occupational disease in the United States. OBJECTIVES: The purpose was to test the applicability of the Health Promotion Model to Mexican American workers' use of hearing protection devices. METHOD: A correlational descriptive design and path analysis were used to determine the relationships between cognitive-perceptual factors, modifying factors and use of hearing protection devices. A questionnaire was completed by a total of 119 workers in three garment manufacturing plants. Interviews were conducted with the occupational health nurse or safety director in each plant to determine the policy regarding hearing protection also. RESULTS: Factors that directly influenced the use of hearing protection devices were a clinical definition of health, benefits of and barriers to use of hearing protection devices, self-efficacy in the use of hearing protection devices and perceived health status (R2 =.25, p <.01). An exploratory analysis allowing a direct relationship of modifying factors with the dependent variable explained additional variance in use of hearing protection devices through the contribution of situational factors (R2 =.55, p <.01). CONCLUSIONS: Important factors related to Mexican American workers' use of hearing protection devices were identified to provide direction for nursing interventions. Future research should further test the explanatory capabilities of the Health Promotion Model, explore the importance of situational influences on health behavior, and ensure reliable measures of all model components for this population.

Adult↗
PubMed2001

Balancing speech intelligibility versus sound exposure in selection of personal hearing protection equipment for Chinook aircrews.

BACKGROUND: Aircrews are often exposed to high ambient sound levels, especially in military aviation. Since long-term exposure to such noise may cause hearing damage, selection of adequate hearing protective devices is crucial. Such devices also affect speech intelligibility. When speech intelligibility and hearing protection lead to conflicting requirements, a compromise must be reached. The selection of personal equipment for RNLAF Chinook aircrews is taken as an example of this process. METHODS: Sound attenuation offered by aircrew helmets and ear plugs was measured using a standardized method. Sound attenuation results were used to calculate sound exposure. Objective predictions of speech intelligibility were calculated using the Speech Transmission Index (STI) method. Subjective preference was investigated through a survey among 28 experienced aircrew members. RESULTS: The use of ear plugs in addition to a (RNLAF standard) helmet may lead to a significant reduction of sound exposure. Using ear plugs that offer high sound attenuation, instead of using a less attenuating type, gives a little additional reduction of sound exposure, at the expense of a large reduction in speech intelligibility. Hence, it is better to use 'light' ear plugs. Better performance still is offered by Communications Earplugs, ear plugs featuring integrated miniature earphones. Results from the user preference survey correspond well with objective measurement results. CONCLUSIONS: In the case of the RNLAF Chinook, the best solution is using Communications EarPlugs in combination with a standard helmet. The Chinook case clearly illustrates that hearing protection and speech intelligibility should be treated as connected issues.

Aerospace Medicine↗
PubMed1984

The otolaryngologist and hearing protectors.

There is increasing evidence that hearing conservation programs based on hearing protective devices can be and are effective. Hearing conservation requires effort and all successful programs seem to be based on a mixture of engineering, monitoring, and personal protection.

Audiometry, Pure-Tone↗
PubMed1995

Prevention of noise-induced hearing loss in the Canadian military.

A prospective study was undertaken to investigate the development of noise-induced hearing loss in Canadian military recruits, and to assess the effectiveness of the hearing conservation program currently in place. The participants were 134 men and women, 20 to 30 years of age, employed in four trades, three of these (infantry, artillery, and armour) associated with high noise levels. The data comprised audiometric measurements made at the time of entry and after 3 years of employment, and responses to a questionnaire mainly relating to noise exposure in the workplace and during leisure activities, and the utilization of personal hearing protective devices. The findings showed that group audiograms at entry and at the 3-year recall were characterized by a 6-kHz notch that was indicative of noise-induced hearing loss, although mean threshold values were within normal limits. By the 3-year recall, 11% of the infantry had sustained a mild-to-moderate hearing loss in the left ear, greater than 25-dB HL, that was consistent with the use of small-calibre weapons. Responses to the questionnaire indicated that, while subjects appreciated the potential benefit of wearing hearing protectors, instructions in their proper use and education on the hazards of noise exposure were poor. The results suggested methods to strengthen the existing scheme for hearing conservation to further minimize risk.

Adult↗
PubMed1991

A controlled investigation of in-field attenuation performance of selected insert, earmuff, and canal cap hearing protectors.

A field study assessed the actual spectral noise attenuation achieved by 40 industrial workers wearing four different hearing protection devices (HPDs) while on the job. The effect of two different HPD fitting procedures (subject fit vs. trained fit) on attenuation performance over two three-week periods of protector use was determined. Subjects were retrieved from their workplaces without prior knowledge of when they were to be tested and were not permitted to readjust the fit of their HPDs. Attenuation data were then collected using psychophysical procedures testing real ear attenuation at threshold. Statistical analyses indicated that the earplugs' attenuation significantly improved when training for proper fitting was used, whereas the earmuff and the ear canal cap were relatively insensitive to the training effect. The training was most effective for a slow-recovery foam plug over the three-week period. Results confirmed that laboratory protocols designed to simulate workplace influences on attenuation may not be relied on to yield reasonable estimates of field protection performance of HPDs, particularly for earplugs; however, the laboratory results were much better predictors of field protection for the earmuff. This study also demonstrated that the labeled manufacturers' noise reduction ratings (NRRs) substantially overestimated the actual field attenuation performance.

Adult↗
PubMed1989

An acoustic head simulator for hearing protector evaluation. II: Measurements in steady-state and impulse noise environments.

The attenuation characteristics of hearing protection devices (HPDs) were measured using a modular acoustic head simulator. The effect in changes in the head configuration was assessed in a steady-state diffuse sound field. The use of artificial circumaural skin had a relatively small influence on the insertion loss of earmuffs (max. 6-7 dB at low frequencies). This contrasts to the very large effects found for the artificial intraaural skin on the insertion loss of earplugs (in excess of 40 dB at low frequencies for some devices). Results were also compared with real-ear attenuation at threshold (REAT) data (ANSI S3.19-1974). In general, there is good agreement between the two methods, especially for earmuffs. Design improvements are proposed for earplugs. The result of an exploratory study aimed at measuring the complex (amplitude and phase) insertion loss of HPDs using an impulse noise source are also reported.

Acoustic Stimulation↗
PubMedDate not supplied

Is acculturation related to use of hearing protection?

Noise-exposed employees with limited English skills may pose a special challenge for hearing conservation programs. This pilot field study assessed knowledge, attitudes, and behavior regarding use of hearing protective devices in a largely Hispanic group of 88 workers exposed to industrial noise. Effectiveness of hearing protection was determined through field measurements of personal attenuation ratings. Individual scores on an acculturation scale (first language learned, language at home, degree of literacy in English, preferred language) demonstrated a correlation between a low degree of acculturation and low personal attenuation rating (R2= 0.49, p=0.0001). Low acculturation was also correlated with high-perceived barriers to use of hearing protection (p=0.006). Although neither self reports of self-efficacy nor perceived benefits of hearing protection correlated with personal attenuation rating, perceived barriers to hearing protector use was a significant predictor of hearing protector fit (p=0.05). These results indicate that less acculturated workers may be underutilizing hearing protection in the workplace partly due to perceived barriers to use of hearing protective devices. To be effective, hearing conservation training programs in work sites with an immigrant work force need to address language and cultural barriers to the use of hearing protection.

Acculturation↗
PubMed2006

Predictors of hearing protection use for Hispanic and non-Hispanic White factory workers.

The 2000 United States Census reported significant growth in the number of Hispanic workers. The National Institute for Occupational Safety and Health (NIOSH, 1996) has identified noise-induced hearing loss as a significant occupational threat. Current theoretical models need to be evaluated for their utility with Hispanic workers. The Predictors for Use of Hearing Protection Model (PUHPM) is a framework for increasing workers' use of hearing protection devices (HPDs). Using regression analysis, the explained variance in HPD use by the model predictors was examined in a sample of 208 Hispanic factory workers. Explained variance was lower for Hispanics (R2 = .20) than for non-Hispanic Whites (R2 = .37). Further research with Hispanic workers is needed to improve the PUHPM fit.

Adult↗
PubMed1975

The effectiveness of hearing protective devices.

The effectiveness of a hearing conservation program, and specifically the effectiveness of hearing protection devices (muffs in this case), was investigated over a five-year period, since the inception of the program at a major plant of the Ingersoll-Rand Company. The study concentrated on three groups (Class I, II, and III) of 213 employees whose noise level exposure did not change during the five-year study period. A hearing conservation criterion of 90dBA was utilized. One group consisted of office workers in which the level was well below this, a second group from a machine shop in which the level was slightly below the criterion, and a third group from foundry areas in which the levels were considerably above the 90dBA level. Personal ear protection was worn during the study period only by the last group. The mean differences in hearing levels were insignificant and were essentially the same in the three groups, at each frequency, and regardless of the baseline hearing thresholds. It is apparent that there were no significant changes in hearing threshodls during the study period among a non-noise exposed group; a mild to moderate noise-exposed group; and a group exposed to high levels of steady state noise, but wearing ear protectors. These results indicate that a hearing conservation program which includes audiometric testing and personal ear protection, utilizing a hearing conservation criterion of approximately 90dBA, does adequately protect the hearing of noise-exposed workers.

Adult↗