BACKGROUND: Different interactional contexts which bilingual speakers encounter place different demands of cognitive control on language processing (Green & Abutalebi, 2013: Adaptive Control Hypothesis; Green, 1998: Inhibitory Control Model). However, how varying cognitive control demands impact lexical access in bilingual persons with aphasia (BPWA) remains unclear. Verbal fluency tasks may provide valuable insights into the interplay between cognitive control and lexical access in BPWA by addressing word generation abilities in language contexts that exert varying degrees of cognitive control effort. AIMS: The present study aimed to examine the performance of BPWA on a semantic category generation task that requires word retrieval in single- and dual-language contexts with varying cognitive control demands and a traditional letter fluency task in single-language contexts. Associations between verbal fluency performance and (i) language use history, and (ii) performance on standardized measures for both BPWA and healthy bilinguals were also examined. METHODS AND PROCEDURES: Twenty-three Spanish-English BPWA and twenty-two Spanish-English healthy bilinguals completed a language use questionnaire, verbal fluency testing and standardized language assessments in each language. The semantic category generation task included four conditions: two conditions examined word retrieval in the first-acquired language (L1) and second-acquired language (L2) in single-language contexts (No Switch-L1 and No Switch-L2) and two conditions elicited word retrieval in dual-language contexts (Self-Switch and Forced-Switch) with low and high cognitive control demands by allowing or restricting switching across languages. The letter fluency task was administered in single-language contexts only (F, A, S for English and P, M, R for Spanish). Verbal fluency performance was compared across conditions and groups using multivariate analyses. Further, correlational analyses were used to examine associations between verbal fluency tasks and bilingual language history and performance on language measures. OUTCOMES AND RESULTS: Overall, the healthy bilinguals outperformed BPWA both in terms of number of correct responses and proportion accuracy across all conditions of the two verbal fluency tasks. However, similar patterns of performance arose when examining performance of the two groups separately. Such that both groups showed reduced performance in the FS condition relative to other conditions (NS-L1, NS-L1, and SS for the healthy bilinguals and SS for the BPWA). However, the BPWA appeared to be more sensitive to the effects of increased cognitive control on lexical access relative to healthy bilinguals, as they also showed reduced performance in the NS-L2 condition compared to the SS condition. Additionally, healthy bilingual produced larger average cluster sizes, number of clusters, and number of switches than BPWA across both verbal fluency tasks. Finally, BPWA and healthy bilinguals’ performance on both verbal fluency tasks was associated with metrics of bilingual language history and language measures. Additionally, for BPWA, verbal fluency performance was associated with measures of cognitive and executive function. CONCLUSIONS: The findings of this study suggest that verbal fluency tasks can help characterize the impact of cognitive control on lexical access in BPWA in single- and dual-language contexts with important clinical implications. / 2022-02-16T00:00:00Z

PURPOSE: Surface electromyography (sEMG) provides an alternative method for individuals with severe motor impairments to use the voluntary contractions of sparred musculature as inputs into an alternative and augmentative communication (AAC) device. Current research suggests that individuals with typical motor control prefer a sEMG-based click mechanism over a dwell-based click mechanism to operate an on-screen cursor. However, there is no existing data on the effects of cursor click modality on language production in AAC users with motor impairments. The goal of this study was to evaluate the communicative abilities of individuals with neuromuscular disorders when using an AAC device with two different cursor click modalities. METHOD: Twelve individuals with neuromuscular disorders produced synthetic language samples via an on-screen keyboard using an sEMG/accelerometer system with two different click modalities: dwell-based clicking and sEMG-based clicking. A third language sample via natural speech was also recorded. Language sample analysis was used to evaluate language complexity at syntactic, semantic, and ideational levels. To analyze syntactic complexity, language samples were examined for clausal density, conjunction usage, phrase expansions (noun phrase, verb phrase, and prepositional phrase), and mean length of utterance. Semantic complexity was analyzed using measures of moving-average type token ratio, abstract noun usage, metacognitive verb usage, and usage of morphologically complex words. Ideational complexity was analyzed in terms of the extent to which the responses conveyed the participant’s ideas. A questionnaire was used to measure the participants’ perceptions of usefulness for each modality. RESULTS: Mean length of utterance was shorter in the dwell-based click modality than in the sEMG-based click and natural speech modalities. In the sEMG-based click modality the majority of sentences were complex sentences, whereas simple sentences made up the majority in the dwell-based click modality. Morphologically complex word usage was used more frequently in the natural speech modality than in the sEMG-based click modality and used most frequently in the dwell-based click modality. There were no modality-specific trends for ideational complexity. Measures from the questionnaire showed that participants ranked natural speech as being more useful than either of the cursor-click modalities, but all three modalities were rated as at least somewhat useful (5 out of 7 on a rating scale of usefulness). CONCLUSION: This study is the first to evaluate the effects of cursor-click modality on the communicative abilities of individuals with neuromuscular disorders. Despite differences in language complexity on some measures, participants were able to use all three modalities to accurately respond to the language prompt with similar ideational scores. These results support both sEMG and dwell as alternative access methods for controlling a cursor-click system for individuals with neuromuscular disorders in future AAC applications.

PURPOSE: The purpose of this study was to evaluate change in mean fundamental frequency (fo) and estimated vocal tract length (VTL) after laryngeal manual therapy and laryngeal reposturing with voicing in a group of transmasculine speakers, a group for which current research is lacking. METHOD: Fifteen transmasculine individuals were recruited for this study. Participants were recorded at baseline (timepoint 1), again after 15 minutes of laryngeal manual therapy (timepoint 2), and again after 15 minutes of laryngeal reposturing with voicing (timepoint 3). Recordings consisted of the following: 1) elongated productions of “pot, seed, coop, cat, hut” to isolate the vowel sounds /ɑ, i, u, æ, ʌ/; 2) a 30–60 second spontaneous speech sample. Mean fo was calculated from the speech samples and VTL was estimated using an average of the third and fourth formants calculated from the middle of the vowel /ʌ/ in “hut.” Two separate repeated measures analyses of variance were completed for mean fo and estimated VTL with main effects of timepoint, followed by post hoc t tests. RESULTS: The repeated measures analyses of variance showed a statistically significant effect of timepoint on fundamental frequency and on estimated VTL. Tukey simultaneous tests for differences of mean fo across timepoints found significance between timepoints 3 and 2. Tukey simultaneous tests for differences of estimated VTL across timepoints found significance between timepoints 3 and 1. CONCLUSION: Laryngeal reposturing with voicing and laryngeal manual therapy together led to a significant increase in estimated vocal tract length, and laryngeal reposturing with voicing led to a significant decrease in mean fo. Individual outcomes varied, but overall results showed effectiveness for the use of these intervention techniques in the treatment of transmasculine individuals seeking gender-affirming voice care.

The present intervention study explores the immediate and delayed word learning in 14 children with cochlear implants. Capitalizing on the multimedia options available in electronic storybooks, the intervention incorporates elements such as videos and illustrations to support a vocabulary intervention that includes evidence-based teaching strategies. The extent of the children's word learning was assessed using three assessment tasks that required an increasing level of word understanding; receptive pointing, expressively labeling and word defining. Children demonstrated greater immediate word learning gains for words taught in the treatment condition compared to those in the comparison condition, across the expressive labeling task. The children's performance on delayed post-test vocabulary assessments did not indicate better retention across receptive and expressive vocabulary tasks for words taught within the treatment condition compared to the comparison condition. Findings suggest that children with cochlear implants can benefit from an oral only multimedia enhanced intensive vocabulary instruction. / A Dissertation submitted to the Department of Communication Science and Disorders in partial fulfillment of the Doctor of Philosophy. / Spring Semester, 2015. / February 27, 2015. / cochlear implants, electronic storybooks, intervention, vocabulary / Includes bibliographical references. / Carla Wood, Professor Directing Dissertation; Michael Kaschak, University Representative; Ramonda Horton, Committee Member; Beth Phillips, Committee Member.

Perceptual adaptation to a talker allows listeners to efficiently resolve inherent ambiguities present in the speech signal introduced by the lack of a one-to-one mapping between acoustic signals and intended phonemic categories across talkers. In ideal listening environments, preceding speech context has been found to enhance perceptual adaptation to a talker. However, little is known regarding how perceptual adaptation to speech occurs in more realistic listening environments with background noise. The current investigation explored how talker variability and preceding speech context affect identification of phonetically-confusable words in adverse listening conditions. Our results showed that listeners were less accurate and slower in identifying mixed-talker speech compared to single-talker speech when target words were presented in multi-talker babble, and that preceding speech context enhanced word identification performance under noise both in single- and mixed talker conditions. These results extend previous findings of perceptual adaptation to talker-specific speech in quiet environments, suggesting that the same underlying mechanisms may serve to perceptually adapt to speech both in quiet and in noise. Both cognitive and attentional mechanisms were proposed to jointly underlie perceptual adaptation to speech, including an active control process that preallocates cognitive resources to processing talker variability and auditory streaming processes that support successful feedforward allocation of attention to salient talker-specific features.

Phonetic variability across talkers imposes additional processing costs during speech perception, evident in performance decrements for mixed- vs. single-talker speech. However, within-talker phonetic variation across different utterances is another, relatively unexplored source of variability in speech, and it is unknown how processing costs from within-talker variation compare to those from between-talker variation. Because cognitive consequences of talker variability are typically measured from two-alternative forced- choice tasks, whereas naturalistic speech processing occurs in a much larger decision space, it is also unclear how the effects of across-talker and within-talker variability scale and interact when there are more options to choose between during word identification. Here, we measured response times in a speeded word identification task that factorially manipulated three dimensions of speech variability: number of talkers (one vs. four), number of target word choices (two vs. six), and number of talker-specific exemplars per word (one vs. eight). Across all eight experimental levels, larger decision spaces led to significantly slower word identification. Word identification was also slower in conditions with mixed talkers and conditions with multiple exemplars. However, performance decrements between mixed- vs. single-talker speech were only present when variability in the other two dimensions was low, but decrements between multi- vs. single-token speech were present under all conditions. This pattern of interactions suggests complex processing relationships between type, token, and talker variability and provides preliminary evidence for how both within- and between-talker variability impose additional processing costs in speech perception.

Reduced abilities in talker identification are observed when listeners are presented with the voices of familiar talkers while in an unfamiliar emotional tone. Despite the acoustic variations caused by different emotional states, listeners tend to demonstrate extraordinary abilities in matching the voices to their corresponding talkers, which suggests their perceptual constancies of voice-identity correspondence. However, the distinctive acoustic-perceptual correlates contributing to the formation of perceptual constancy have been rarely studied from the aspect of within-talker variability (i.e., how do listeners know they are hearing the same talkers when many of the key acoustic features of their voices are inconsistent across different contexts?). This study investigated the influence of variation in the emotional tone of voice on listeners’ abilities for talker identification. We explicitly trained our participants with five voices in an emotional state and tested their generalization abilities in talker identification by presenting them with the same talkers’ voices in the trained emotional state and the other untrained emotional state. Our results showed that listeners were more accurate when they were presented with trained emotional states than untrained emotional states. The improved accuracy supported that listeners benefitted from their early experience with the voices across multiple contexts to form their constant perceptual representations of voice identities. We also observed a significant correlation between the difference of mean fundamental frequency (f0) and accuracy, suggesting the differences of mean f0 tended to be a distinctive parameter to quantify the invariant features in the vocal signals.

Despite the ambiguous many-to-many mapping between acoustic signals and target phonemes, human listeners quickly overcome and adapt to inconsistencies during speech perception. However, the processing cost of speech perception increases when a change of the talker occurs and preceding context speech was found to reduce the processing cost. The magnitude of the response time difference between the single- and mixed-talker condition is called the interference effect. The literature indicates that that the interference effect is reduced by increasing length of speech context preceding target speech, but the quantity of the information embedded in that speech context does not further impact processing cost. In this study, we further explored the relationship between the duration of the preceding speech context and its facilitative effect in talker adaptation. The results indicated that even though response times were always shorter in the single-talker condition than the mixed-talker condition, the facilitative effect of preceding context speech became constant for durations longer than beyond 600ms, rather than eventually eliminating the interference effect at some carrier phrase of sufficient duration. Therefore, wo mechanisms are proposed to subserve talker adaptation: a feed-forward, extrinsic process that reduces the interference effect by integrating prior speech context of up to 600ms, and a top-down, intrinsic process that unfolds over longer timescales by allocating cognitive resources to cope with potential talker variability, leading to a global processing time increase.

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PURPOSE: The purpose of this study was to investigate the relationship between auditory-perceptual measures of monopitch and acoustic correlates, and to compare these measures between a group of participants with Parkinson’s disease (PwPD) and a control group of age- and sex-matched participants without Parkinson’s disease. METHOD: Twenty listeners rated 60 recordings of speakers (30 PwPD, 30 controls) on degree of monopitch using a VAS. An acoustic correlate was derived by tracking the difference between fundamental frequency variations at final and non-final unit boundaries (foVUBdiff) in the 60 speech recordings. RESULTS: PwPD were rated as having a higher degree of monopitch and were found to have a lower foVUBdiff when compared to the control group. A statistically significant relationship between auditory-perceptual measures of monopitch and acoustic correlate was found. CONCLUSION: This study revealed the following: (1) PwPD were found to have higher auditory-perceptual ratings of monopitch when compared to the control group; (2) PwPD were found to have less foVUB at non-final unit boundaries and less foVUBdiff between unit boundaries when compared to the control group; (3) There is a correlation between the auditory-perceptual measures of monopitch and acoustic correlate. Together, these findings suggest that the acoustic correlate, foVUBdiff taken across unit boundaries in The Rainbow Passage shows promise as an objective measure of perceived monopitch.