456 subjects were enrolled into the study; of these, 63 are students (controls), and 393 are construction apprentices. Subject recruitment is now closed.

Click here to see subject enrollment by subject group.

Click here for a detailed summary of data collection through the end of Year 3.

599 two-day activity cards have been returned to date. These cards allow subjects to report their activities and noise exposures over a 40-hour period, and are essential to the project, as they give us an idea of what each subject's noise exposure is like throughout the study.

Click here to see a table of the number of cards returned by subject group.

128 noise dosimetry sessions have been recorded to date. These data allow us to capture the noise exposure that subjects experience over a 40-hour period, and to correlate these findings with activities reported on the two-day activity cards.

Click here to see a table of the number of noise measurements by subject group.

Click here to see a bar graph of noise levels by subject group

Click here to see a report on noise exposure in the general public