Effects of age on concurrent vowel perception in acoustic and simulated electroacoustic hearing

Purpose: In this study, the authors investigated the effects of age on the use of fundamental frequency differences (ΔF₀) in the perception of competing synthesized vowels in simulations of electroacoustic and cochlear-implant hearing. Method: Twelve younger listeners with normal hearing and 13 older listeners with (near) normal hearing were evaluated in their use of ΔF₀ in the perception of competing synthesized vowels for 3 conditions: unprocessed synthesized vowels (UNP), envelope-vocoded synthesized vowels that simulated a cochlear implant (VOC), and synthesized vowels processed to simulate electroacoustic stimulation (EAS) hearing. Tasks included (a) multiplicity, which required listeners to identify whether a stimulus contained 1 or 2 sounds and (b) double-vowel identification, which required listeners to attach phonemic labels to the competing synthesized vowels. Results: Multiplicity perception was facilitated by ΔF₀ in UNP and EAS but not in VOC, with no age-related deficits evident. Double-vowel identification was facilitated by ΔF₀, with ΔF ₀ benefit largest in UNP, reduced in EAS, and absent in VOC. Age adversely affected overall identification and ΔF₀ benefit on the double-vowel task. Conclusions: Some but not all older listeners derived ΔF₀ benefit in EAS hearing. This variability may partly be due to how listeners are able to draw on higher-level processing resources in extracting and integrating cues in EAS hearing.