DPOAE level from two newborn and three adult subjects in black and gray lines, respectively. Averaged noise floors for each group are presented using thinner lines in the same color. These subjects from each group were selected to represent the general limits of DPOAE level in each group.
Comparison of DPOAE fine structure in one member from each age group. These two subjects were chosen to represent examples of “deep” fine structure from each group. The frequency range marked by the horizontal dashed line allows direct comparison of approximately three fine structure periods in the two subjects. The noise floor from each subject is also displayed.
Comparisons of various estimates of DPOAE levels as a function of frequency. Error bars represent standard deviation. (A) Comparison of average DPOAE level estimated using three different methods in ten newborns along with an estimate of the average noise floor (see the text). (B) Average DPOAE levels for ten newborns and ten young adults as a function of frequency. (C) Average DPOAE levels for each age group separated by sex. Symbols are “jittered” around the nominal frequency points on the abscissa to enhance visual clarity.
Total number of fine structure periods observed in all (left) ten newborns and (right) ten young adults. Data from female and male subjects are presented in open and shaded bars, respectively. The main effect of sex was statistically significant (see Table I).
Fine structure depth as a function of frequency. Open circles and gray triangles represent individual data points from newborn and young adult subjects, respectively. Mean values of fine structure computed over ranges are displayed using the black circles and triangles for the newborns and young adults, respectively. The symbols representing the mean values are jittered along the abscissa for visual clarity. The error bars represent standard deviation. The main effect of age group was statistically significant (see Table I for details).
Distribution of fine structure depth for the two age groups separated by sex. (Left) Data from the newborns with female and male subjects represented using open and gray bars, respectively. (Right) The format is repeated for the young adult subjects. Fine structure periods are grouped in bins based on the measured depth. The main effect of sex was statistically significant (see Table I for details).
Fine structure spacing computed as (see the text for explanation) as a function of frequency. The format is identical to that of Fig. 5. Larger numbers along the ordinate represent narrower fine structure periods. The main effect of age group was statistically significant (see Table I for details).
Distribution of fine structure spacing in each age group and sex. The format is identical to that of Fig. 6.
Prevalence of log-sine and non-log-sine fine structure periods in each age group and sex. (Top) Examples of each type of fine structure period. (Bottom) The bars represent the total number of fine structure periods observed in each age group divided by sex. The white and gray portions within each bar represents the number of log-sine and non-log-sine periods observed in each group, respectively.
Results of multiway ANOVA with age group, sex, and frequency as the independent variables and either DPOAE level, fine structure prevalence, depth, or fine structure spacing as the dependent variables. Interactions between age group and frequency as well as between sex and frequency were not statistically significant for any dependent variable. To arrive at the mean DPOAE level estimates, a minimum of 20 data points (around ) and a maximum of 85 data points (around ) were averaged. The number of data points used in the analyses involving fine structure parameters at any frequency depended on prevalence and are shown in Figs. 4–8.
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