جستجوی مقالات مرتبط با کلیدواژه « روش میکروفن داخل گوش » در نشریات گروه « پزشکی »

Nominal noise reduction rating of the earmuff manufacturers can be different compared with the actual noise attenuation rating. The current study aimed to determine the actual noise reduction rate of current hearing protection devices in the real workplaces using a field microphone in real ear method (FMIRE).
In this cross-sectional study, five common earmuffs were studied in both industrial environments with different noise nature on the 50 workers who were selected randomly. Noise reduction ratings of ear muffs were measured based on the ISO 11904 standard, microphone in real ear method, using noise dosimeter (SVANTEK, model SV 102) equipped with a microphone SV 25 model which can install inside the ear. In addition, the knowledge, attitudes and performance of employees about hearing protection were assessed by the developed questionnaire. Data was analyzed by SPSS 21.
Independent of the type of noise exposure, actual insertion loss values for ear muffs in one octave-band frequency was less than the nominal insertion loss values. Actual noise reduction rates of the earmuffs in the exposed of dominant noise low frequency are less than the nominal reduction rates (p The frequency nature of noise is very impressive on the actual noise reduction rates can be achieved from earmuffs. Therefore, data about the frequency analysis of ambient noise is key ingredient when selecting hearing protectors in any workplaces. FMIRE could facilitate rapid and simple measurement of the actual acoustic performance of earmuffs in real conditions of industrial environments.

One of the recommended methods for evaluation effectiveness of hearing protection is use the acoustic fixture accordance with standard ISO 4869-3. The aim of this study was evaluate the acoustic performance of fixture for using in noise reduction rate tests of hearing protection devices in the laboratory.
In this cross-sectional study , noise reduction rates of five common ear muffs used in the Iran industries were investigated based on the ISO 11904 standard, microphone in real ear method, using noise dosimeter (SVANTEK , Model SV102) equipped with microphone SV25 model which can install inside the ear on 30 subjects under laboratory conditions. Also, noise reduction rate of earmuffs was determined using the fixture model AVASINA9402 accordance with standard procedures. Data were analyzed using the software SPSS21.
The results showed the real noise reduction rates of the earmuffs on the studied subjects are from 59% to 94% nominal reduction rates. That rates for the ear muffs on the studied fixture are from 64% to 92.The results showed that the noise reduction rates of the ear muffs on subjects compared with and noise reduction rates of the ear muffs on fixture were not statistically significant (p> 0.05).
The results showed the accuracy of noise reduction rate of earmuffs using the fixture compared with real subjects is acceptable. Hence, the fixture is good choice for environments where there’s no possibility of acoustic evaluation on real subjects, also for quality control of productions in the earmuff manufacturers.