Demographics
Table 1 shows the demographics of the volunteers who had enrolled into the study to date and who had downloaded at least once, compared to all 1074 workers enrolled in hearing conservation programs at the three study facilities. As the table shows, compared to the larger population, volunteers as a group are slightly older and with worse baseline hearing thresholds, and also more likely to be of Hispanic ethnicity and report a history of hunting and shooting. The average tenure was similar between the two groups, in excess of 16 years on the job, indicating that shows that many of the volunteers likely had significant noise exposure prior to enrolling in the study. The proportion of Hispanic workers was higher at the turbine factory site (data not shown). The 39 total volunteers who either left employment or left the study were similar demographically to those that remained in the study.