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Comparative Study
. 2011 Feb;54(1):190-210.
doi: 10.1044/1092-4388(2010/09-0145). Epub 2010 Aug 5.

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

Kathryn H Arehart  1 , Pamela E Souza, Ramesh Kumar Muralimanohar, Christi Wise Miller
Affiliations
Comparative Study

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

Kathryn H Arehart et al. J Speech Lang Hear Res. 2011 Feb.

Abstract

Purpose: In this study, the authors investigated the effects of age on the use of fundamental frequency differences (ΔF(0)) 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 ΔF(0) 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 ΔF(0) in UNP and EAS but not in VOC, with no age-related deficits evident. Double-vowel identification was facilitated by ΔF(0), with ΔF(0) benefit largest in UNP, reduced in EAS, and absent in VOC. Age adversely affected overall identification and ΔF(0) benefit on the double-vowel task.

Conclusions: Some but not all older listeners derived ΔF(0) 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.

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Figures

Figure 1
Figure 1
Audiograms of younger group and older group of listeners.
Figure 2
Figure 2
Processing for the VOC condition (top panel) and the EAS (bottom panel) condition. VOC = envelope-vocoded synthesized vowels that simulated a cochlear implant; EAS = synthesized vowels processed to simulate electroacoustic (EAS) hearing.
Figure 3
Figure 3
Proportion of trials in which listeners reported hearing two voices for blocks of trials containing both same-vowel–same-F0 and same-vowel–different-F0 stimuli. Average results are shown for the younger and older groups of listeners in the UNP, EAS, and VOC conditions. Error bars represent the standard error. Chance performance (guessing) would correspond to 0.5 instances of “two voices” reported.
Figure 4
Figure 4
Proportion of trials in which listeners reported hearing two vowels for trials actually containing two different vowels (double vowels). Average results are shown for the younger and older groups of listeners in the UNP, EAS, and VOC conditions. Chance performance (guessing) would correspond to 0.5 instances of “two vowels” reported. Results are also shown for single-vowel trials (SV). Error bars represent the standard error.
Figure 5
Figure 5
Proportion of trials in which listeners correctly identify both vowels contained in a double-vowel stimulus. Average results are shown for the younger and older groups of listeners in the UNP, EAS, and VOC conditions. Error bars represent the standard error. Chance performance is 10%.
Figure 6
Figure 6
Proportion of trials in which listeners correctly identify both vowels contained in a double-vowel stimulus. Results are shown for individual listeners in the UNP, EAS, and VOC conditions. Chance performance is 10%.
Figure 7
Figure 7
ΔF0 benefit (defined as proportion of double-vowel correct at 4 ST minus proportion of double-vowel correct at 0 ST) for individual listeners in the older group (left panel) and in the younger group (right panel) for the UNP, EAS, and VOC conditions. Subjects are ordered based on the amount of ΔF0 benefit in the UNP condition.
Figure 8
Figure 8
Scatterplot of ΔF0 benefit in the EAS condition plotted against the ΔF0 benefit in the UNP condition.
See this image and copyright information in PMC

References

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