Masking level difference for speech: effects of ear dominance and age.

A comparison was made of right and left ear discrimination of monosyllables presented with competing 'cocktail party' in conditions of signal monaural-noise monaural, and signal monaural-noise binaural and in-phase interaurally. The effects of these conditions were compared in 20 normal children aged 5-6 years, 40 normal young adults and 20 adults aged 66-76 years. The magnitudes of right and left ear masking level differences (MLDs) were compared at each age level. (1) MLDs occurred for all three age groups; (2) for the two adult age groups, mean right ear scores exceeded mean left ear scores in the case of monaural noise presentation, although the difference was significant only for the young adults; (3) no interaural difference appeared for the children, and (4) marked variability of the magnitude of the MLDs occurred among subjects of all three age groups.