Distribution of pretest audiometric PTA for each group. The -axis has been flipped to resemble an audiogram. Dotted horizontal lines indicate the median. Boxes demark the 25th and 75th percentiles. Asterisks show actual data points. (Data with identical values show as a single asterisk). Data from both ears of each subject are included, so that (9 subjects), 20 (10 subjects), and 22 (11 subjects) for the treatment, placebo, and control groups, respectively.