Elisabet Classon

Dynamic Relation Between Working Memory Capacity and Speech Recognition in Noise During the First 6 Months of Hearing Aid Use

The present study aimed to investigate the changing relationship between aided speech recognition and cognitive function during the first 6 months of hearing aid use. Twenty-seven first-time hearing aid users with symmetrical mild to moderate sensorineural hearing loss were recruited. Aided speech recognition thresholds in noise were obtained in the hearing aid fitting session as well as at 3 and 6 months postfitting. Cognitive abilities were assessed using a reading span test, which is a measure of working memory capacity, and a cognitive test battery. Results showed a significant correlation between reading span and speech reception threshold during the hearing aid fitting session. This relation was significantly weakened over the first 6 months of hearing aid use. Multiple regression analysis showed that reading span was the main predictor of speech recognition thresholds in noise when hearing aids were first fitted, but that the pure-tone average hearing threshold was the main predictor 6 months later. One way of explaining the results is that working memory capacity plays a more important role in speech recognition in noise initially rather than after 6 months of use. We propose that new hearing aid users engage working memory capacity to recognize unfamiliar processed speech signals because the phonological form of these signals cannot be automatically matched to phonological representations in long-term memory. As familiarization proceeds, the mismatch effect is alleviated, and the engagement of working memory capacity is reduced.

Hearing impairment, cognition and speech understanding: exploratory factor analyses of a comprehensive test battery for a group of hearing aid users, the n200 study

Abstract Objective: The aims of the current n200 study were to assess the structural relations between three classes of test variables (i.e. HEARING, COGNITION and aided speech-in-noise OUTCOMES) and to describe the theoretical implications of these relations for the Ease of Language Understanding (ELU) model. Study sample: Participants were 200 hard-of-hearing hearing-aid users, with a mean age of 60.8 years. Forty-three percent were females and the mean hearing threshold in the better ear was 37.4 dB HL. Design: LEVEL1 factor analyses extracted one factor per test and/or cognitive function based on a priori conceptualizations. The more abstract LEVEL 2 factor analyses were performed separately for the three classes of test variables. Results: The HEARING test variables resulted in two LEVEL 2 factors, which we labelled SENSITIVITY and TEMPORAL FINE STRUCTURE; the COGNITIVE variables in one COGNITION factor only, and OUTCOMES in two factors, NO CONTEXT and CONTEXT. COGNITION predicted the NO CONTEXT factor to a stronger extent than the CONTEXT outcome factor. TEMPORAL FINE STRUCTURE and SENSITIVITY were associated with COGNITION and all three contributed significantly and independently to especially the NO CONTEXT outcome scores (R2 = 0.40). Conclusions: All LEVEL 2 factors are important theoretically as well as for clinical assessment.

Early ERP Signature of Hearing Impairment in Visual Rhyme Judgment.

[This corrects the article on p. 241 in vol. 4, PMID: 23653613.].Postlingually acquired hearing impairment (HI) is associated with changes in the representation of sound in semantic long-term memory. An indication of this is the lower performance on visual rhyme judgment tasks in conditions where phonological and orthographic cues mismatch, requiring high reliance on phonological representations. In this study, event-related potentials (ERPs) were used for the first time to investigate the neural correlates of phonological processing in visual rhyme judgments in participants with acquired HI and normal hearing (NH). Rhyme task word pairs rhymed or not and had matching or mismatching orthography. In addition, the inter-stimulus interval (ISI) was manipulated to be either long (800 ms) or short (50 ms). Long ISIs allow for engagement of explicit, top-down processes, while short ISIs limit the involvement of such mechanisms. We hypothesized lower behavioral performance and N400 and N2 deviations in HI in the mismatching rhyme judgment conditions, particularly in short ISI. However, the results showed a different pattern. As expected, behavioral performance in the mismatch conditions was lower in HI than in NH in short ISI, but ERPs did not differ across groups. In contrast, HI performed on a par with NH in long ISI. Further, HI, but not NH, showed an amplified N2-like response in the non-rhyming, orthographically mismatching condition in long ISI. This was also the rhyme condition in which participants in both groups benefited the most from the possibility to engage top-down processes afforded with the longer ISI. Taken together, these results indicate an early ERP signature of HI in this challenging phonological task, likely reflecting use of a compensatory strategy. This strategy is suggested to involve increased reliance on explicit mechanisms such as articulatory recoding and grapheme-to-phoneme conversion.

Combined Effects of Form- and Meaning-Based Predictability on Perceived Clarity of Speech

The perceptual clarity of speech is influenced by more than just the acoustic quality of the sound; it also depends on contextual support. For example, a degraded sentence is perceived to be clearer when the content of the speech signal is provided with matching text (i.e., form-based predictability) before hearing the degraded sentence. Here, we investigate whether sentence-level semantic coherence (i.e., meaning-based predictability), enhances perceptual clarity of degraded sentences, and if so, whether the mechanism is the same as that underlying enhancement by matching text. We also ask whether form- and meaning-based predictability are related to individual differences in cognitive abilities. Twenty participants listened to spoken sentences that were either clear or degraded by noise vocoding and rated the clarity of each item. The sentences had either high or low semantic coherence. Each spoken word was preceded by the homologous printed word (matching text), or by a meaningless letter string (nonmatching text). Cognitive abilities were measured with a working memory test. Results showed that perceptual clarity was significantly enhanced both by matching text and by semantic coherence. Importantly, high coherence enhanced the perceptual clarity of the degraded sentences even when they were preceded by matching text, suggesting that the effects of form- and meaning-based predictions on perceptual clarity are independent and additive. However, when working memory capacity indexed by the Size-Comparison Span Test was controlled for, only form-based predictions enhanced perceptual clarity, and then only at some sound quality levels, suggesting that prediction effects are to a certain extent dependent on cognitive abilities.

Relations between Concurrent Longitudinal Changes in Cognition, Depressive Symptoms, Self-Rated Health and Everyday Function in Normally Aging Octogenarians

Ability to predict and prevent incipient functional decline in older adults may help prolong independence. Cognition is related to everyday function and easily administered, sensitive cognitive tests may help identify at-risk individuals. Factors like depressive symptoms and self-rated health are also associated with functional ability and may be as important as cognition. The purpose of this study was to investigate the relationship between concurrent longitudinal changes in cognition, depression, self-rated health and everyday function in a well-defined cohort of healthy 85 year olds that were followed-up at the age of 90 in the Elderly in Linköping Screening Assessment 85 study. Regression analyses were used to determine if cognitive decline as assessed by global (the Mini-Mental State Examination) and domain specific (the Cognitive Assessment Battery, CAB) cognitive tests predicted functional decline in the context of changes in depressive symptoms and self-rated health. Results showed deterioration in most variables and as many as 83% of these community-dwelling elders experienced functional difficulties at the age of 90. Slowing-down of processing speed as assessed by the Symbol Digits Modality Test (included in the CAB) accounted for 14% of the variance in functional decline. Worsening self-rated health accounted for an additional 6%, but no other variables reached significance. These results are discussed with an eye to possible preventive interventions that may prolong independence for the steadily growing number of normally aging old-old citizens.

Erratum: Early ERP signature of hearing impairment in visual rhyme judgment

This General Commentary provides a corrected version of Figure ​Figure6,6, page 10. The topographical map of the group with hearing impairment in the 100–300 ms time-window and R–O– condition has been corrected. Figure ​Figure66 shows the topographical distribution of the grand averaged ERPs in the normal hearing (NH) and hearing-impaired (HI) groups in the 100–300, 300–500, and 500–700 ms time-windows, long ISI. The rows show the distribution over the R+O+, R+O−, R−O+, and R−O− rhyme task conditions. Figure 6 Topographical distribution of the grand averaged ERPs in the normal hearing (NH) and hearing-impaired (HI) groups in the 100–300, 300–500, and 500–700 ms time-windows, long ISI. The rows show the distribution over the R+O+, R+O−, ...