[The use of masking level differences in evaluating central auditory processing: the norms for the normal hearing subjects].
OBJECTIVE
This study sought to determine whether scores of masking level differences (MLD) were influenced by age and sex and to derive norm values from normal hearing subjects for the Turkish population.


METHODS
A total of 100 normal hearing subjects were tested in two age groups. Each group consisted of 25 females and 25 males. The mean ages were 21 (range 17 to 24 years) and 31 years (range 25 to 40 years) in group 1 and group 2, respectively. Following pure-tone threshold and speech discrimination tests, the MLD test was performed by using 500 Hz pure-tone and narrow-band noise centered around 500 Hz. The results were analyzed by the ANOVA test.


RESULTS
The mean MLD score was 10.92 dB. The upper and lower limits of MLD scores between two standard deviations were 6 and 14 dB, respectively. No significant differences were found between MLD scores with regard to age and sex.


CONCLUSIONS
Since MLD scores are not affected by age and sex, the norm values obtained can be utilized in the investigation of some pathologic conditions.
Department of Psychology, Audiology and Speech Sciences and Perception Laboratory, Ankara, Turkey.
Ayşe Gül
AG
Güven
Murad
M
Mutlu
D000161:Acoustic Stimulation / Q000379:methods; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D005260:Female; D006309:Hearing / Q000502:physiology*; D006320:Hearing Tests; D006801:Humans; D008297:Male; D010470:Perceptual Masking / Q000502:physiology*