Evaluation of Noise Attenuation and Verbal Communication Capabilities Using Three Ear Insert Hearing Protection Systems Among Airport Maintenance Personnel

Abstract

The goal of this project was to determine whether one type of earplug would allow a user to hear communication in a noisy environment better than two other types of earplugs. The three types of earplugs studied are newly available on the market. Sonomax SonoCustoms are custom fitted to the user. E-A-R Push-Ins are the newest form of foam earplugs, and Howard Leight SmartFits have an adaptable shape. One of the earplug manufacturers claimed to have improved verbal communications due to the design of the earplug. We hypothesized that the type of earplug providing better communication properties would have lower attenuation around the communication frequencies compared with the other types. To test this hypothesis, we used speech intelligibility and attenuation tests in the laboratory on 26 subjects, and real-time video exposure monitoring in the field (airport maintenance personnel) for visual communication cues. ANCOVA was used to analyze the data from the laboratory study. The type of earplug worn was not significant in the model (p-value 0.0849), nor was attenuation of the earplug (p-value 0.2379). Further analysis showed that attenuation did not differ significantly among earplugs (p-value 0.5903). Logistic regression was used to analyze the data from the field study. Again, the type of earplug was not significant in the model (p-value 0.0965). A comfort questionnaire determined that Howard Leight SmartFits and the E-A-R Push-Ins were more comfortable and easier to use than the Sonomax HPDs (p-value <0.0001). We found a definite difference between manufacturers' attenuation data and our attenuation data, especially in the frequencies for 125–1000 Hz. Also, there was no difference in frequency and overall attenuation among the HPDs. This resulted in no difference in communication abilities among the types of HPDs.

Keywords:

• airport
• attenuation
• communication
• earplugs
• hearing protection devices

ACKNOWLEDGMENTS

The authors are grateful to the employees at the Purdue and American Trans Air airport maintenance facilities for their outstanding assistance and cooperation throughout the project. LW thanks NIOSH for the fellowship opportunity to pursue a master's degree in industrial hygiene at Purdue University.

Notes

^A Four subjects were used for the field study; however, their identification number remained the same as in the laboratory study.

^B The Sonomax listed here is for the full block; the filter was not used for the field study.

^A Total Score is determined by multiplying the weight by the total number of responses for each answer, then summing them for each HPD.

^B Average is determined by dividing the total score by the total number of responses.