Binaural advantage for younger and older adults with normal hearing

Three experiments measured benefit of spatial separation, benefit of binaural listening, and masking-level differences (MLDs) to assess age-related differences in binaural advantage.

Participants were younger and older adults with normal hearing through 4.0 kHz. Experiment 1 compared spatial benefit with and without head shadow. Sentences were at 0 degrees, and speech-shaped noise was at 0 degrees, 90 degrees, or +/-90 degrees. Experiment 2 measured binaural benefit with the near ear unplugged compared with plugged for sentences at 0 degrees and masker at 90 degrees. Experiment 3 measured MLDs under earphones for 0.5-kHz pure tones in Gaussian and low-noise noise, and spondees in speech-shaped noise.

Spatial-separation benefit for speech did not differ significantly for younger and older adults but was smaller than predicted by an audibility-based model for older adults and larger than predicted for younger adults. Binaural listening benefit was observed for younger participants only. Tonal MLDs suggested that listeners benefit from interaural difference cues during noise dips for signals out of phase. Neither tonal nor speech MLDs differed significantly between younger and older participants.

Binaural processing of sentences revealed some age-related deficits in the use of interaural difference cues, whereas no deficits were observed for more simple detection or recognition tasks.