Consistency of attenuation across multiple fittings of custom and non-custom earplugs.

Hearing protection devices (HPDs) play a significant role in protecting workers from occupational noise-induced hearing loss. Individual HPD fit-testing estimates the amount of protection, or attenuation, that an individual achieves from a given HPD as it is worn. Results from a single fit-test may not be representative of real-world HPD performance over time, however, due to inconsistency in how the individual fits the HPD from time to time. In this study, the effects of HPD type and user training on the consistency of attenuation achieved across multiple fittings were evaluated in a within-subjects design. Attenuation measurements using a real-ear attenuation at threshold procedure were obtained on 30 participants wearing custom-molded and non-custom earplugs. The subjects were initially naive to proper earplug insertion techniques and later received one-on-one training for the second half of the attenuation measurements. Consistency, or reliability, of fit was assessed using (i) the standard deviation of the 'distance to ear mean attenuation', a measure of fitting uncertainty, and (ii) the standard deviation of the attenuation values across multiple fit-tests for each subject. The custom earplug provided statistically significantly better consistency of attenuation than the non-custom earplug at 500, 1000, and 2000 Hz. Training effects were statistically significant at 250, 500, and 1000 Hz and at the Personal Attenuation Rating. No interactions were statistically significant. These results indicate that, in general, subjects obtained more consistent attenuation with the custom earplugs than with the non-custom earplugs and that consistency improved with training for both earplug types.

Hearing protection for clubbers is music to their ears.

ISSUE ADDRESSED: while it is difficult to promote the use of hearing protectors in noisy workplaces and leisure settings, some nightclub attendees choose to wear earplugs when exposed to loud music. This qualitative study investigated the perceptions of clubbers about the advantages and disadvantages of earplug use in nightclubs. Such first-hand information could potentially be used to educate non-wearers about the features of different earplug types, the experience of wearing earplugs and their relative merits. METHODS: structured telephone interviews were conducted with 20 regular clubbers who wear different types of earplugs at nightclubs. Participants were asked about their experience of wearing earplugs and, in particular, what they perceive to be the advantages and disadvantages of earplugs. RESULTS: participants' responses revealed that cheaper foam earplugs are considered less satisfactory than more expensive earplugs, which are relatively discreet and comfortable, facilitate communication with others, create minimal music distortion and, in some cases, improve music sound quality. In terms of effectiveness, all types of earplugs were considered beneficial in reducing the after-effects of loud music and providing hearing protection. CONCLUSIONS: the perceived advantages of earplugs, which are often not recognised by non-earplug wearers, should be communicated in order to encourage the use of earplugs among clubbers.

[Polymeric hearing protectors in sport shooting]. / Polimerowe ochronniki sluchu w strzelectwie sportowym.

Using hearing protectors during exposition to noise is fundamental to hearing loss prevention. The optimal choice of hearing protectors should take into consideration not only the physical characteristics of the acoustic environment which imply the traumatic action of noise, but also some individual preferences of the user. All contemporary produced hearing protectors both earmuffs as well as earplugs are made of synthetic polymers e.g. ABS, polyvinylchloride, polyethylene, polyurethathane, silicone rubbers. The type of the material used determines hardness, incompressibility and plasticity of the hear protector and may cause some discomfort. A special group of individuals exposed to noise are sport shooters in which (whose) case the exposition to impact noise is several times higher above standards. The aim of this work was an appraisal of the individual preferences in the choice of hearing protectors. The properties of polymers used for the production of hearing protectors were also taken into consideration. 104 females and 93 males representing master class were interviewed in this study. The analysis of the answers indicated that abandoning of hearing protectors by some shooters is due to the frequent skin irritations, overheating in the ear canal and allergy. Shooters linked these problems with the materials used for the production of hearing protectors. Earplugs were preferred by females, whereas males indicated earmuffs as their preferred choice. Females preferred earplugs made of soft materials which can be easily fitted to ear canal. Those males who used earplugs preferred protectors made of hard plastics as they thought this make better insulation. It can be concluded that the choice of the hearing protectors should not be done on the basis acoustic signal characteristics only, but also should reduce some discomforts resulting from properties of the materials used for their production.

Attenuating properties of hearing protectors in versus time factor.

In the noisy environment, workers use hearing protectors to protect their hearing organ against adverse effects of noise. Hearing protectors should be well selected according to the spectrum and level of noise. The selection of hearing protectors is based on the sound attenuation values measured in laboratory conditions. Workers usually use hearing protectors provided by employers as long as there are no signs of any physical damage. The aim of this study was to assess the effect of use and storage as well as of atmospheric conditions on sound attenuation of ear-muffs. Four models of ear-muffs popular in the Polish work environment were tested for two years. They fulfilled the PN-EN 352-1 standard requirements and were granted a certification mark. Fifteen samples of each model were used by workers every working day; 10 samples were exposed to natural atmospheric conditions; and 10 samples were stored in accordance with the manufacture's advice. Temperature and humidity were checked each day. After periods of one and two years, sound attenuation was measured according to PN-EN 24869-1 standard. The observed changes in high-frequency attenuation value H. medium-frequency attenuation value M, low-frequency attenuation value L and single number rating calculated according to PN - EN ISO 4869-2, are presented. The quantitative assessment how far the period of use, storage and exposure to natural atmospheric conditions affect protection achieved by the four popular models of ear-muffs is presented.

[The determination of the criteria for selecting and using personal means of acoustic protection]. / Determinazione dei criteri per la scelta e la utilizzazione dei mezzi personali di protezione acustica.

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.

Hearing protection: surpassing the limits to attenuation imposed by the bone-conduction pathways.

With louder and louder weapon systems being developed and military personnel being exposed to steady noise levels approaching and sometimes exceeding 150 dB, a growing interest in greater amounts of hearing protection is evident. When the need for communications is included in the equation, the situation is even more extreme. New initiatives are underway to design improved hearing protection, including active noise reduction (ANR) earplugs and perhaps even active cancellation of head-borne vibration. With that in mind it may be useful to explore the limits to attenuation, and whether they can be approached with existing technology. Data on the noise reduction achievable with high-attenuation foam earplugs, as a function of insertion depth, will be reported. Previous studies will be reviewed that provide indications of the bone-conduction (BC) limits to attenuation that, in terms of mean values, range from 40 to 60 dB across the frequencies from 125 Hz to 8 kHz. Additionally, new research on the effects of a flight helmet on the BC limits, as well as the potential attenuation from deeply inserted passive foam earplugs, worn with passive earmuffs, or with active-noise reduction (ANR) earmuffs, will be examined. The data demonstrate that gains in attenuation exceeding 10 dB above the head-not-covered limits can be achieved if the head is effectively shielded from acoustical stimulation.

Nuevos desarrollos en protección auditiva / New development in hearing protection

La protección auditiva personal sigue siendo un tema importante en la prevención del daño auditivo por el ruido, especialmente en el medio laboral y deportivo. Los protectores convencionales son una respuesta probadamente suficiente pra la mayoría de los casos, pero existen situaciones que requieren de protectores con dispositivos especiales que transformen la señal acústica que van a transmitir. La actual tecnología ofrece protectores no convencionales pasivos y activos, éstos últimos con sistemas electrónicos de procesamiento. Pueden actuar como filtros para determinadas frecuencias o bien cancelando la onda sonora por superposición contra onda en diferente fase. También se utilizan dispositivos para facilitar la comunicación entre portadores de protectores auditivos. Su utilidad es manifiesta pra las personas que requieren una audición precisa de señales de alarma, o bien del lenguaje oral, o si padecen de hipoacusia perceptiva con descenso de umbrales auditivos en las frecuencias agudas. Se analizan los métodos más modernos de evaluar la atenuación de los protectores, sus deficiencias y las ventajas comparativas, insistiendo en la necesidad de su conocimiento por parte de quienes deben indicar su uso dentro de un programa de conservación de la audición

Protectores auditivos / Hearing protector

El elevado porcentaje de trabajadores afectados por altos niveles de ruido hace que la hipoacusia inducida por ruido (HIR) sea uno de los problemas más graves que afronta la medicina del trabajo. Seleccionar el protector auditivo adecuado para cada caso particular, es una de las medidas más rápidas y eficaces para prevenir el daño producido por el ruido. Colaborar para lograrlo es el objetivo del presente trabajo