highly significantP < 0.001
A Friedman’s analysis of variance (ANOVA) with Bonferroni correction of the difference suppression values at different test frequencies in the total participants group indicated a statistically less suppression for 4000 Hz compared to 2828 Hz ( P < 0.03) and highly significant difference between the following frequencies: 4000 and 2000 Hz ( P < 0.001); 4000 and 1001 Hz ( P < 0.001); 4000 and 1414 Hz ( P < 0.001); 2828 and 2000 Hz ( P < 0.001); 2828 and 1001 Hz ( P < 0.001) and 2000 and 1001 Hz ( P < 0.001).