Release from Multiple Maskers in Elderly Persons

Masked thresholds for spondees were measured in 27 binaural conditions covering homophasic, antiphasic, parallel time-delayed, and opposed time-delayed listening in the presence of one to three competing maskers. One of the maskers was white noise modulated four times per second by 10 dB with 50% duty cycle; the other two were sentences spoken by different male talkers. These stimuli were variously combined to produce seven masker conditions. Subjects were 10 young adults, 23 women aged 70 to 85 years, and 22 men aged 63 to 88 years. Masking level differences (re homophasic performance) were observed in every instance of dichotic presentation. MLDs for the young adults were usually somewhat larger than those for the elderly subjects. Both groups showed (1) somewhat larger MLDs when the competing background included two talkers, (2) somewhat smaller MLDs during time-delay modes, and (3) smaller MLDs in opposed time-delay than in parallel time-delay. This last feature was particularly noteworthy for the elderly listeners, whose MLDs during opposed time delay averaged only 2.3 dB.