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PubMed1989

An exploratory study of moderate physical activity and selected design attribute effects on earmuff attenuation.

Hearing protective devices are tested for their attenuation characteristics under controlled laboratory conditions. Unfortunately, these tests overestimate the typical attenuation performance of the devices in the field, posing the possibility of inadequate protection for the user. Many factors may affect achieved in-field attenuation. This research investigated the influence of the user's work-related movement and variations in headband compression force and earcup cushion material (liquid- or foam-filled) on the frequency-specific noise attenuation achieved with earmuffs. Real-ear attenuation at threshold (REAT) testing procedures were used to collect attenuation data on 24 subjects both prior to and following completion of a simulated work task. Statistical analyses indicated that moderate work-related movement significantly decreased low-frequency attenuation but by only a small amount (1.5 dB at 125 Hz). A high headband compression force was found to increase attenuation by approximately 1.5 to 4 dB at 125, 250, 500, and 8000 Hz. There was no significant difference at any frequency between cushion types. The results indicate a small effect of moderate physical work activity on hearing protector effectiveness and illustrate the importance of certain earmuff design parameters to achieved attenuation.

Ear Protective Devices↗
PubMed1979

The effectiveness of hearing protectors in practice.

A series of workmen being evaluated for pensions for occupational hearing loss were asked to bring their own hearing protectors from work, to fit them themselves, following which attenuation studies were made. The muffs and most earplugs produced similar attenuation levels at high frequencies, although the muffs produced less attenuation at low frequencies. In all cases the mean attenuation was significantly lower than optimum figures suggested in the literature, and the standard deviation was relatively high. Personally molded earplugs were significantly less effective than other plugs used. Reasons are discussed for the relatively poor performance of these devices and the concept of assumed protection, i.e. mean minus one standard deviation, is discussed. There is need for better instruction on how to use hearing protectors if they are to be effective.

Adult↗
PubMed1997

Active noise reduction versus conventional hearing protection. Relative benefits for normal-hearing and impaired listeners.

The benefits of active noise reduction (ANR) hearing protectors were assessed in two groups of normal-hearing subjects, under and over the age of 40 years, and one group with bilateral high-tone hearing loss. Subjects were tested with the ears unoccluded and fitted with conventional sound attenuating E-A-R foam plugs, E-A-R HI-FI plugs, and Bilsom Viking muffs; and one ANR muff, the Peltor 7004. Within each ear condition, measurements were made in quiet of hearing thresholds for frequencies between 0.25 kHz and 8 kHz, duration and frequency difference limens, and word recognition. Hearing thresholds and word recognition were also measured in a background of impulsive cable swager noise. The E-A-R foam plug provided the highest and the E-A-R HI-FI plug, the lowest attenuation. The Bilsom Viking and Peltor muffs were virtually identical and midway between. An additional 10 dB of sound reduction was realized at 0.25 kHz with ANR. The masking effect of the noise on hearing threshold decreased with an increase in attenuation. None of the devices compromised either duration or frequency discrimination. Word recognition in noise improved in normal listeners when protectors were worn. For the impaired subjects, word recognition with poor contextual cues decreased with an increase in sound attenuation, in both quiet and noise. Like older normal listeners, their scores were relatively higher with ANR.

Adult↗
PubMed2000

Use of active noise cancellation devices in caregivers in the intensive care unit.

OBJECTIVE: Recent development of noise cancellation devices may offer relief from noise in the intensive care unit environment. This study was conducted to evaluate the effect of noise cancellation devices on subjective hearing assessment by caregivers in the intensive care units. DESIGN: Randomized, double-blind. SETTING: Adult medical intensive care unit and pediatric intensive care unit of a teaching hospital. SUBJECTS: Caregivers of patients, including nurses, parents, respiratory therapists, and nursing assistants from a medical intensive care unit and pediatric intensive care, were enrolled in the study. INTERVENTION: Each participant was asked to wear the headphones, functional or nonfunctional noise cancellation devices, for a minimum of 30 mins. MEASUREMENTS: Subjective ambient noise level was assessed on a 10-point visual analog scale (VAS) before and during headphone use by each participant. Headphone comfort and the preference of the caregiver to wear the headphone were also evaluated on a 10-point VAS. Simultaneously, objective measurement of noise was done with a sound level meter using the decibel-A scale and at each of nine octave bands at each bedspace. RESULTS: The functional headphones significantly reduced the subjective assessment of noise by 2 (out of 10) VAS points (p < 0.05) in environments of equal objective noise profiles, based on decibel-A and octave band assessments. CONCLUSION: Noise cancellation devices improve subjective assessment of noise in caretakers. The benefit of these devices on hearing loss needs further evaluation in caregivers and critically ill patients.

Adult↗
PubMed2004

Effect of electronic ANR and conventional hearing protectors on vehicle backup alarm detection in noise.

An experiment was conducted wherein masked thresholds (using ascending method of limits) for a backup alarm were obtained in pink and red noise at 85 and 100 dBA for 12 participants immersed in a probability monitoring task and wearing a conventional passive hearing protection device (HPD, an earmuff or a foam earplug), an active noise reduction (ANR) headset, or no HPD at all (only in 85 dBA noise). Results revealed statistically significant between-HPD differences in red noise (from 2.3 to 3.1 dB) and in the 100-dBA noise level (from 2.6 to 4.3 dB). An additional finding, which corroborates other studies using different protocols, was that masked thresholds in 85-dBA noise were significantly lower (from 3.2 to 4.4 dB) for the occluded conditions (wearing an HPD) than for the open-ear (unoccluded) condition. This result refutes the belief among many normal-hearing workers that the use of HPDs in relatively low levels of noise compromises their ability to hear necessary workplace sounds. Actual or potential applications of this research include (a) the selection of appropriate HPDs for low-frequency-biased noise exposures wherein signal detection is important and (b) gaining insight into the appropriateness of ANR-based HPDs for certain industrial noise environments.

Adolescent↗
PubMed2006

Variability of real-world hearing protector attenuation measurements.

The attenuation provided by a hearing protection device (HPD) in the field is usually estimated by applying a derating factor to the laboratory-determined noise reduction rating (NRR) of the HPD. However, attenuation is highly dependent on individual-specific HPD fit. Prediction of an individual's attenuation depends on the accuracy of the measurement system and the variability of attenuation over time (e.g. after HPD refitting). Variability in attenuation and attenuation test systems has not been adequately characterized to allow for such an assessment. This study compared attenuation measurements made with two systems, Real-Ear-at-Threshold (REAT) and Microphone-in-Real-Ear (MIRE), on 20 workers using two earplugs (foam and custom-molded). Workers' perceptions of the earplugs were also evaluated. Individuals' attenuation results were summarized as personal attenuation ratings (PARs, similar to NRRs). Variability in PARs from between-subject, within-subject and within-day (i.e. repeated tests on a subject without earplug refitting) differences was assessed and used to present the lower confidence limit, or uncertainty factor (UF), of an average individual's attenuation. The custom-molded earplug PARs achieved a higher mean percentage of labeled attenuation than did the foam earplug with both test systems. The custom-molded earplugs also had higher overall acceptance among workers. MIRE PAR levels were lower than REAT levels for both earplugs, but the relationship between the two test systems was highly variable. The MIRE system had lower within-day variability than the REAT system. One individual's MIRE results were highly influential; removal of these results greatly reduced the UF for the custom-molded earplug/MIRE combination. UFs ranged from 8.8 to 13.5 dB. These findings highlight the importance of evaluating variability in individual-specific protection results for personal protective equipment like HPDs, rather than relying on single measurements.

Ear Protective Devices↗
PubMed1999

Effects of earplugs and protective headgear on auditory localization ability in the horizontal plane.

The purpose of this study was to determine how well humans localize sound sources in the horizontal plane while wearing protective headgear with and without hearing protection. In a source identification task, a stimulus was presented from 1 of 20 loudspeakers arrayed in a semicircular arc, and participants stated which loudspeaker emitted the sound. Each participant was tested in 8 conditions involving various combinations of wearing a Kevlar army helmet and two types of earplugs. Testing was conducted at each of 2 orientations (frontal and lateral). In the frontal orientation, overall error was slightly greater in all protected conditions than in the bare-head control condition. In the lateral orientation, overall error score in the protected conditions was substantially and significantly greater than in the bare-head control conditions. Most errors in the lateral orientation were accounted for by front-back confusions, indicating that the protective devices disrupted high-frequency spectral cues that are the basis for discriminating front from back sound sources. The results have practical implications for the use of protective headgear and earplugs in industrial or military environments where localization of critical sounds is important.

Adult↗
PubMedDate not supplied

Understanding barriers to preventive health actions for occupational noise-induced hearing loss.

A theoretically based formative evaluation was conducted with coal miners in the Appalachian Mountains who were at high risk for noise-induced hearing loss (NIHL). The results of four focus groups indicate that despite high levels of knowledge, strong perceived severity of negative consequences, and strong perceived susceptibility to hearing loss, two main categories of barriers (environmental and individual) keep coal miners from using their hearing protection devices (HPD). Further analysis suggests that the environmental factors, rather than individual variables, more strongly influence decisions against protective actions. Recommendations and practical implications are offered.

Adult↗
PubMedDate not supplied

The use of hearing protectors among forest, shipyard and paper mill workers in Finland--a longitudinal study.

From 1953 to 1995 the usage rate of hearing protective devices (HPD) was tracked at a paper mill, a shipyard, and in selected areas of forestry work. For each work period, observations were made of HPD use among workers. In the paper mill, the usage rate increased steadily from 1965. In 1990, 39% of workers used HPDs full-time. At the shipyard, the usage rate remained low up to the mid-1980s, but thereafter the proportion of full-time users rose to 70%. A similar trend was noted in forest workers, with the full-time use at 97% by the 1990s. Due to the increased usage rate in all measured industries, the mean effective noise level at the ear has decreased to below 85 dB.

Cross-Sectional Studies↗
PubMedDate not supplied

[The determination of the criteria for selecting and using personal means of acoustic protection].

The most frequent occupational disease in Italy is noise-induced hearing loss. Not only is this disease invalidating and irreversible, it also involves extremely high direct and indirect costs for both the injured worker and the employer. Appropriate preventive measures are therefore essential and include personal protection devices. Recent Italian legislation (DL 277 15/8/91) assigns an important role to personal acoustic protection devices, raising, in certain situations, serious problems in terms of fitness for specific jobs. On the basis of an analysis of the characteristics of the various types of hearing protection aids, including efficacy, capacity of attenuation, influence on intelligibility of speech and perception of danger signals, guidelines are supplied for their best possible use.

Auditory Perception↗
PubMed1995

Audibility of reverse alarms under hearing protectors for normal and hearing-impaired listeners.

The question of whether or not an individual suffering from a hearing loss is capable of hearing an auditory alarm or warning is an extremely important industrial safety issue. The ISO Standard that addresses auditory warnings for workplaces requires that any auditory alarm or warning be audible to all individuals in the workplace including those suffering from a hearing loss and/or wearing hearing protection devices (HPDs). Research was undertaken to determine how the ability to detect an alarm or warning signal changed for individuals with normal hearing and two levels of hearing loss as the levels of masking noise and alarm were manipulated. Pink noise was used as the masker and a heavy-equipment reverse alarm was used as the signal. The rating method paradigm of signal detection theory was used as the experimental procedure to separate the subjects' absolute sensitivities to the alarm from their individual criteria for deciding to respond in an affirmative manner. Results indicated that even at a fairly low signal-to-noise ratio (0 dB), subjects with a substantial hearing loss [a pure-tone average (PTA) hearing level of 45-50 dBHL in both ears] were capable of hearing the reverse alarm while wearing a high-attenuation earmuff in the pink noise used in the study.

Adult↗
PubMedDate not supplied

Creating a tailored, multimedia, computer-based intervention.

Tailoring of health-related messages is effective in motivating behavior change. However, planning, designing, and implementing a tailored health promotion program can be a challenge. This article describes the process of creating a tailored multimedia program for presentation via computer to promote factory workers' use of hearing-protection devices to prevent noise-induced hearing loss. The creation process was segmented into 5 phases: 1) determination of program content; 2) creation of overall program design, including live action and still video and addition of sound and graphics; 3) development and integration of tailoring pathways into the final intervention; 4) development of a database and participant handouts; and 5) pilot testing of the intervention program. The approach used in this research program can serve as a prototype for future development of computerized multimedia health promotion interventions and can assist others in the effective use of this medium.

Algorithms↗
PubMed2007

Hearing threshold shift measured by otoacoustic emissions after shooting noise exposure in soldiers using hearing protectors.

OBJECTIVE: The aim of the study was to assess the influence of short-term impulse noise to temporary threshold shift in soldiers using hearing protectors. STUDY DESIGN AND SETTING: The study included 80 subjects with correct tympanic membrane and thresholds measured by pure-tone audiometry less than 20 dB. There were two groups: 40 soldiers protected during shooting and 40 young males who didn't shoot. TEOAE were performed by ILO 292 Echoport Otodynamics device 3 to 5 minutes before shooting and 2 minutes and 1, 2, and 3 hours after shooting. RESULTS: Short-term exposure to impulse noise generated by five gunshots from the rifle kbk AKMS hasn't induced temporary threshold shift of hearing for chosen frequencies in soldiers using hearing protectors. Spectral analysis for chosen frequencies revealed that measurement reproducibility, stimuli level, and probe stability appeared to be comparable and repeatable. CONCLUSION: Our results show that the use of hearing protectors safeguarded against impulse noise. SIGNIFICANCE: The use of earmuffs is strongly recommended because they seem to sufficiently attenuate shooting noise.

Adult↗
PubMed1992

Effectiveness of earplugs in high-intensity impulse noise.

The efficiency of different types of earplugs was assessed by means of Békésy audiometry following the exposure of 42 human subjects to weapon impulses. The peak pressure of the impulses ranged from 2.3-27.8 kPa (from 161 to 183-dB peak SPL) and the A-weighted equivalent level (over 8 h) of each exposure ranged from 100-114 dB. All subjects wore earplugs fitted by an experienced individual. The devices tested included one brand of conventional foam earplugs and a number of different models of perforated earplugs, one type of which had been previously shown to provide nonlinear attenuation. Perforated earplugs were tested because they provide better speech communication than conventional passive earplugs, and in the nonlinear case also afford attenuation that increases with the peak pressure of the impulses. The temporary threshold shifts (TTSs) observed in these experiments were very small and indicated no significant hazard for hearing. Well-fitted perforated earplugs seem to be able to protect the ear from infrequent exposures to the high-level impulses produced by small and large weapons while allowing good speech communication, and without impairing the operational capacity of soldiers who must remain aware of their acoustic environment.

Adult↗
PubMed1986

The use of acoustical test fixtures for the measurement of hearing protector attenuation. Part I: Review of previous work and the design of an improved test fixture.

This paper gives a comprehensive progress report on the development of objective methods for measuring the attenuation of hearing protection devices (HPD's), and focuses on the use of acoustic test fixtures (ATF's), i.e., artificial heads. While there are many publications on ATF's for the evaluation of circumaural HPD's (earmuffs), only one serious attempt to construct an ATF for the evaluation of intra-aural HPD's (earplugs) could be found. Consequently, no ATF for testing earplugs has been standardized so far, while two standardized ATF's currently exist for testing earmuffs [see ANSI S3.19-1974 (1975) and ISO/DIS 6290 (1983)]. Both ATF's are suited, however, only for production testing and are not designed for HPD-type testing. It is believed that both ATF's do not provide sufficiently high accuracy for HPD-type testing. A new ATF with appropriate circumaural and intra-aural flesh simulations was constructed, including a suitable ear simulator and a cast of an average pinna. Objectives for design and construction of the new ATF are discussed. The effect of using artificial flesh on the insertion loss of earmuffs (max. 5 dB at 125 and/or 250 Hz) and the effect of using a pinna (max. 12 dB lower insertion loss at 2 kHz) were evaluated.

Auditory Threshold↗
PubMed2005

Amplified earmuffs: impact on speech intelligibility in industrial noise for listeners with hearing loss.

PURPOSE: To determine how amplified earmuffs affect the intelligibility of speech in noise for people with hearing loss, and to determine how various brands of amplified earmuffs compare in terms of speech intelligibility and electroacoustic response. METHOD: The Hearing in Noise Test (HINT) was used to measure the intelligibility of speech for 10 participants with hearing loss when they listened in a background of recorded industrial noise at 85 dBA. Participants listened with 3 different sets of amplified earmuffs (Peltor Tactical 7-S, Elvex COM 55, and Bilsom 707 Impact II), with a set of passive earmuffs (E-A-R Ultra 9000), and with ears unoccluded. Two measurements of sentence threshold were obtained under each of the 5 listening conditions. Gain was measured electroacoustically across a range of input levels and frequencies for each amplified earmuff. RESULTS: Electroacoustic measurements indicated that each electronic earmuff amplified at low input levels and attenuated at high input levels. However, gain characteristics varied greatly across devices. HINT sentence thresholds were not significantly different across the 5 listening conditions or across the 2 trials. CONCLUSION: Results suggest that each type of earmuff can be used to reduce the noise exposure of people with hearing loss without compromising their ability to understand speech.

Acoustic Impedance Tests↗
PubMed1996

Usefulness of the protection motivation theory in explaining hearing protection device use among male industrial workers.

The present study examined the usefulness of personal variables: noise annoyance, and components of the protection motivation theory (R. W. Rogers, 1983) along with social-organizational factors in explaining hearing protection device (HPD) use among Israeli manufacturing workers. Participants were 281 men exposed to harmful noise levels for which routine HPD use is required by regulation. In practice, 3 HPD user groups were identified: nonusers (n = 38), occasional users (n = 125), and regular users (n = 118). HPD use was objectively verified. HPD use was primarily related to the personal variables but not to management pressure, coworker pressure, or family support. The most powerful predictors of HPD use were perceived self-efficacy (for long-term HPD use), perceived susceptibility (to hearing loss), and noise annoyance, together explaining 48% of the outcome variance. These findings have implications for interventions aimed at motivating workers to use HPDs regularly.

Adolescent↗
PubMed1994

Knowledge and attitudes of a group of South African mine workers towards noise induced hearing loss and the use of hearing protective devices.

The study aimed to explore the knowledge and attitudes of a group of mine workers regarding noise induced hearing loss and the use of hearing protective devices. These aims were investigated via a questionnaire administered in a group setting to 55 underground mine workers. The main finding that emerged from the study was that respondents were poorly informed regarding the fact that noise was a health hazard. Furthermore, the knowledge that respondents did possess, appeared to have been derived from the personal experience of working in noisy environments for many years, rather than from educational input. Contrary to expectations, respondents did not view deafness as a status symbol but rather as a negative attribute. Consequently, they were motivated to protect themselves from hearing impairment and to be educated about hearing and the effects of noise. The mine workers complained about discomfort when wearing hearing protective devices as well as feelings of insecurity due to inhibition of communication and the inability to hear warning signals. For these reasons, noise protection was mainly worn in situations perceived as noisy by workers themselves. These results are discussed in terms of their implications for the clinical practice of audiology; hearing conservation in the mining industry; further research; and the training and education of speech-language pathologists and audiologists.

Ear Protective Devices↗