Interventions to promote the wearing of hearing protection

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Evaluation of hearing protection used by police officers in the shooting range

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Application of an auditory steady-state response test to evaluate the attenuation of hearing protection devices

This research aims to present a new method to get real attenuation of hearing protection devices, with good reproducibility and a small standard deviation, without relying on skills and cooperation individual. Thus the authors performed tests in 10 individuals without protection and after with two kinds of ear protections (ear plug and ear muffs), to get the threshold limit value in each of the 3 stages. For this, the research used an electrophysical exam, normally used in speech therapy, named ASSR (auditory steady-state response). The principle of this exam is put on individual’s head 3 electrodes, to capture electrical signs directly in auditory nerve. In summary, the authors presented the final results. The method proposed by ANSI (American National Standards Institute) indicated an attenuation of 27.6 dB for ear plugs, while the value found in this work was 16 dB; and for ear muffs, the ANSI method indicated 29.8 dB while the value found here was 28.5 dB.

Effects of hearing protector devices on speech intelligibility

The purpose of this study was to determine the influence of hearing protection devices (HPDs) on the understanding of speech in young adults with normal hearing, both in a silent situation and in the presence of ambient noise. The experimental research was carried out with the following variables: five different conditions of HPD use (without protectors, with two earplugs and with two earmuffs); a type of noise (pink noise); 4 test levels (60, 70, 80 and 90 dB[A]); 6 signal/noise ratios (without noise, + 5, + 10, zero, - 5 and - 10 dB); 5 repetitions for each case, totalling 600 tests with 10 monosyllables in each one. The variable measure was the percentage of correctly heard words (monosyllabic) in the test. The results revealed that, at the lowest levels (60 and 70 dB), the protectors reduced the intelligibility of speech (compared to the tests without protectors) while, in the presence of ambient noise levels of 80 and 90 dB and unfavourable signal/noise ratios (0, -5 and -10 dB), the HPDs improved the intelligibility. A comparison of the effectiveness of earplugs versus earmuffs showed that the former offer greater efficiency in respect to the recognition of speech, providing a 30% improvement over situations in which no protection is used. As might be expected, this study confirmed that the protectors' influence on speech intelligibility is related directly to the spectral curve of the protector's attenuation. (C) 2003 Elsevier B.V. Ltd. All rights reserved.

Aplicação de exame de resposta auditiva de estado estável para avaliação da atenuação de protetores auriculares

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Reconhecimento da perda de eficácia de protetor intra-auricular

Among the harmful health agents, it is given to the noise, one of the most present in urban and social environments. There are efficient measures to control the noise and the auricular Individual Protection Equipment (IPEa) is the most used. It has been observed the shortage in the comfortable and functional individual auditory protection products, related to durability, face to the efficiency right of the equipment. The main objective of this study was to recognize if there is effectiveness loss toward the used time on the Auditory Equipment, intra-auricular Individual Protection, of foam (3M), model 1110. It has been verified that the equipments suffer efficiency alteration according to the time of use, and the material consuming initiates reliable loss, mainly in audible frequencies going up to 100Hz, and from 16 days for sonorous pressure suffered started in 101dB 20Hz. For sonorous pressure suffered from 107dB to 20Hz, the reliable loss for the usage was of 8 days. The IPEas do not lose effectiveness on important attenuation by the daily use in frequencies from 1KHz until 20KHz. It has been concluded that there is effectiveness loss, according to the daily and frequent use of the IPEa studied.