Speech Recognition in Adults With Cochlear Implants: The Effects of Working Memory, Phonological Sensitivity, and Aging

Abstract

Purpose: Models of speech recognition suggest that "topdown" linguistic and cognitive functions, such as use of phonotactic constraints and working memory, facilitate recognition under conditions of degradation, such as in noise. The question addressed in this study was what happens to these functions when a listener who has experienced years of hearing loss obtains a cochlear implant. Method: Thirty adults with cochlear implants and 30 agematched controls with age-normal hearing underwent testing of verbal working memory using digit span and serial recall of words. Phonological capacities were assessed using a lexical decision task and nonword repetition. Recognition of words in sentences in speech-shaped noise was measured.Results: Implant users had only slightly poorer working memory accuracy than did controls and only on serial recall of words; however, phonological sensitivity was highly impaired. Working memory did not facilitate speech recognition in noise for either group. Phonological sensitivity predicted sentence recognition for implant users but not for listeners with normal hearing. Conclusion: Clinical speech recognition outcomes for adult implant users relate to the ability of these users to process phonological information. Results suggest that phonological capacities may serve as potential clinical targets through rehabilitative training. Such novel interventions may be particularly helpful for older adult implant users.

Visual working memory span in adults with cochlear implants: Some preliminary findings

“… 7 , 8 , 9 The role that working memory plays in speech skills among adult CI users has received some attention with regard to word and sentence recognition and sentence comprehension, but remains poorly understood. 10 , 11 , 12 …”

Middle Latency Responses to Optimized Chirps in Adult Cochlear Implant Users

“…By contrast, we did not find a significant correlation between MLR features and speech recognition abilities in the present study. Speech perception relies on an interactive process between linguistic, cognitive, and social information, where a vast neural network contributes to the analysis of the different aspects of the speech stimulus (Moberly et al, 2017;Alemi et al, 2018). Therefore, it is perhaps not surprising that we could not find any evidence linking speech perception abilities to a single electrophysiological metric that is likely driven by a minority of these processes.…”

“…Although it has been documented that experience with CI leads to a significant improvement in speech perception ability, especially during the first year of CI use (Blamey et al, 2013;Moberly et al, 2017), it does not imply that objective MLR measures are necessarily directly related to this ability. To our knowledge, only one study to date has shown a significant correlation between interelectrode amplitude variations (and latency measures) with speech perception scores (Groenen et al, 1997).…”

Prognostics Factors of Cochlear Implant in Adults: How Can We Improve Poorer Performers?

“…Conceptually, rehabilitation can be divided into two approaches, top-down or bottom-up [23]. Methods that focus on bottom-up procedures utilize materials relating specifically to the input signals possible via a CI, that is, how a signal is processed.…”

“…Thus, cognitive factors play a large role in the wide variance seen in performance scores obtained by the adult CI population. Optimizing a personalized rehabilitation strategy must take into consideration the cognitive dynamics of speed of processing, working memory, and attention and executive function [23].…”