Hearing Protectors, Safety Glasses, and Respiratory Protective Equipment in Combination: Effect on Sound Attenuation
| Principal investigator(s): | Sharon M. Abel (Mount Sinai Hospital) |
| Co-investigator(s): | Andrea Sass-Kortsak (University of Toronto) |
| Sponsoring Institution: | Mount Sinai Hospital |
For more information about this study please contact Dr. Sharon M. Abel at e-mail: sharon.abel@drdc-rddc.gc.ca
Results
The results of this study showed that for each of five protective conditions, the noise reduction provided by earmuffs increases as frequency increases from 0.25 kHz to 1 kHz, after which there was no further increase.
Five Hearing Test Conditions
1. earmuffs mounted on a hard hat,
2. earmuffs on the hard hat and with safety glasses
3. earmuffs mounted on a hard hat and with a respirator,
4. earmuffs on the hard hat with both the glasses and respirator, and
5. no earmuffs, glasses or respirator
The greatest noise reduction occurred with the muff on the hard hat alone, and the least noise reduction occurred with the muff on the hard hat used in combination with the safety glasses and the respirator. The difference between these two conditions was greatest at the lowest frequencies tested (0.25 and 0.5 kHz).
Generally, noise reduction was slightly greater for men than for women. All subjects had significantly poorer consonant discrimination in a noisy environment, compared to quiet, but this was worse for those subjects with an existing hearing loss. Hearing-impaired subjects also performed more poorly when wearing the muffs.
Conclusions
These results demonstrate that wearing other protective safety gear around the head can interfere with the hearing protection provided by earmuffs. They also show that for people with a hearing loss, the use of earmuffs might increase the handicap.
Objective
This study was designed to determine whether the hearing protection provided by earmuffs would be reduced by wearing them in combination with other safety gear also worn around the head area (e.g. hard hats, safety glasses, respirators)
Methods
Seventy-two working age subjects (36 men and 36 women) were included in the study. In both groups, 12 subjects were under the age of 40 and had normal hearing. 24 subjects were over the age of 40; 12 with normal hearing and 12 with hearing loss typical of the damage caused by exposure to noise.
Two kinds of tests were performed on each subject. The ability to hear sounds was determined by measuring diffuse field hearing thresholds in quiet, and at 8 different frequencies ranging from 0.25 kHz to 8.0 kHz. The second test measured the ability to discriminate consonants in quiet and in the presence of background noise.
These two tests were performed on each subject five times:
- with earmuffs mounted on a hard hat,
- with earmuffs on the hard hat and with safety glasses,
- with earmuffs mounted on a hard hat and with a respirator,
- with earmuffs on the hard hat with both the glasses and respirator, and
- with no earmuffs, glasses or respirator.
Publications
Abel, S.M., Sass-Kortsak, A., and Kielar, A. (2002). “The effect on earmuff attenuation of other safety gear worn in combination.” Noise & Health 5:1-13.
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