Figure 2: Pure-tone hearing thresholds as a function of frequency for the onsite (Quantico) and baseline (Walter Reed) measurements. Data have been excluded for subjects 10, 11, and 15, who did not participate in at least one on-site collection and one baseline collection. The error bars show 95% confidence intervals around each data point. The *indicates a frequency that where there was a significant difference at the P<0.05 level, and the **indicates a frequency that was significantly different at the P<0.005 level