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Simulations of Control Strategies to Reduce Sound Exposures of Music Instructors

Abstract No:

1713

Abstract Type:

Student Poster

Authors:

K Crawford¹, R Anthony¹

Institutions:

¹University of Iowa, Iowa City, IA

Presenter:

Kathryn Crawford, MS
University of Iowa

Faculty Advisor:

Renee Anthony, PhD, CIH
University of Iowa

Description:

We used Monte Carlo simulations to create sound exposure profiles for instructors and then simulated the effects of wearing hearing protection devices (HPD) to assess how effective they would be in reducing exposure.

Situation/Problem:

Music instructors typically experience highly variable levels of sound, some of which are loud enough to cause hearing damage. Because there is a lot of variability in their sound exposure, and they need to hear well at all times, we need to recommend practical and effective strategies that can be used to reduce their risk of hearing loss. Two main issues with recommending HPD is that we have to rely on the user to wear the HPD and we do not know what level of attenuation an individual user may achieve. If users do not achieve a good fit or they do not wear the HPD then they will not be effective in reducing exposures.

Methods:

We collected personal sound exposure measurements from brass music instructors using Casella dBadge2 Pro noise dosimeters for thirty-six workdays. Participants also filled out activity logs indicating what activities they were engaged in throughout the day. Time-stamped sound levels and logs were used to code 30-minute activity blocks and sound equivalent levels (LEQ) were calculated for each 30-minute period. Data were imported into SAS (Cary, NC) and used to generate sound distributions for each activity. Logs were examined to determine the duration and frequency of activities by day and by week. Because day to day activities varied, the average proportions of time spent in activities by week were determined. We used Oracle Crystal Ball to run 5000 Monte Carlo simulations to estimate weekly exposure profiles (LEX-5day) calculated from 80 30-minute blocks for music instructors based on sound distributions for each activity and the proportion of each week spent in those activities. We then used the personal attenuation data collected in our previous study to simulate the effects of wearing two types of hearing protection devices (non-custom and custom uniform attenuation earplugs) during specific activities. We used the median personal attenuation rating study participants achieved for the two types of HPD in simulations (non-custom= 18 dB, custom= 14 dB). We then examined the influence of proportion of time spent wearing HPD (i.e., 25%, 50%, 75%, 95%) to compare the effects on the estimated sound exposure distributions.

Results / Conclusions:

Results: Estimated mean LEX-5day exposures for Brass instructors were 91 dBA (sd=1.0) with a 95th percentile at 92 dBA. Means and 95th percentiles for these weekly exposures remained over 85 dBA unless HPD were worn for 95% of musical activities or if HPD was worn any time a 30-minute activity LEQ >90 dBA. There were no substantial differences between LEX-5day percentiles between custom and non-custom UAE simulations. Simulations of the custom HPD attenuating sound by 14 dB are also of importance because the 5th percentile PAR for the non-custom HPD was also 14 dB. This comparison also then illustrates the difference between an average fit and a poor fit of these earplugs and that there is little difference between the two in terms of weekly exposure level.
Conclusions: Brass instructors are exposed to sound above recommended limits during their weekly activities, requiring HPD use of at least 95% of the time during musical activities to keep weekly exposures (LEX-5day) below 85 dBA. There was no substantial difference in estimated weekly exposures between the two types of HPD we compared. Additionally, the simulations indicate a poor fit (5th percentile=14 dB) compared to an average fit (50th percentile= 18 dB) for the non-custom HPD had similar exposure reductions. This suggests the most important indicator of HPD effectiveness is not fit but an increased likelihood of usage. Future interventions should focus on ways to motivate music instructors to wear HPD more often during music activities or find a way to alert them when sound levels reach 90 dBA so they know to wear HPD.

Primary Topic:

Noise

Secondary Topics:

Exposure Assessment Strategies

Risk Assessment and Management

Co-Authors

Please add your co-authors below. Co-authors are listed for professional courtesy and will not be communicated with regarding the decision notification or any on-site logistics, if accepted. Only the primary presenter listed is expected to attend and present the content on-site.

T. Renee Anthony, CIH, PhD

Acknowledgements and References

List any additional people who worked on the project or provided guidance and support along with details on the role they played in the research. (Please include first name, last name, organization, city, state and country).

Krista Willenbring and Stephanie Fleckenstein, AuD from the Unviersity of Iowa's Department for Communciation Sciences and Disorders (Iowa City, IA, USA). They were both co-authors on the study where we collected the personal attenuation data for the HPD we used in this study.

Practical Application

How will this help advance the science of IH/OH?

These simulations provide a practical way to estimate the effects of potential control strategies on long-term exposures and help inform decisions regarding which strategies would be the most effective in reducing exposures.