Objective: Masking level difference (MLD) tests are an established component of auditory processing test batteries; however, normative data for these tests vary according to procedure. The purpose of this study was to establish a standardized procedure for clinical use in the measurement of the MLD.
Design: A newly developed computer software program using both an adaptive procedure (MLDA) and a Békésy procedure (MLDB) was evaluated in this study.
Study sample: Forty normal-hearing, native-English speaking adults between the ages of 18 and 26 years were included in the study.
Results: Both the MLDA and MLDB procedures showed statistically significant sex differences in the masked thresholds used to obtain the MLD, but not for the calculated MLD value; hence, normative data need not be reported separately by sex. Furthermore, statistically significant differences between procedures were observed, with the MLDA procedure producing higher MLDs. The MLDA procedure permitted a d' analysis, which could not be determined using the MLDB procedure. For MLDA, d' = 1.4, test sensitivity = 96.4%, and test specificity = 60.3%.
Conclusions: The results of this study indicate that MLDA is a more efficient testing procedure due to MLDA's higher MLD average and the statistical data available (d', and measures of sensitivity and specificity).