Cascading influences on the production of speech: evidence from articulation

Ultrasound measurements of interactive turn-taking in question-answer sequences: Articulatory preparation is delayed but not tied to the response

We know that speech planning in conversational turn-taking can happen in overlap with the previous turn and research suggests that it starts as early as possible, that is, as soon as the gist of the previous turn becomes clear. The present study aimed to investigate whether planning proceeds all the way up to the last stage of articulatory preparation (i.e., putting the articulators in place for the first phoneme of the response) and what the timing of this process is. Participants answered pre-recorded quiz questions (being under the illusion that they were asked live), while their tongue movements were measured using ultrasound. Planning could start early for some quiz questions (i.e., midway during the question), but late for others (i.e., only at the end of the question). The results showed no evidence for a difference between tongue movements in these two types of questions for at least two seconds after planning could start in early-planning questions, suggesting that speech planning in overlap with the current turn proceeds more slowly than in the clear. On the other hand, when time-locking to speech onset, tongue movements differed between the two conditions from up to two seconds before this point. This suggests that articulatory preparation can occur in advance and is not fully tied to the overt response itself.

Cascading activation in phonological planning and articulation: Evidence from spontaneous speech errors

Speaking involves both retrieving the sounds of a word (phonological planning) and realizing these selected sounds in fluid speech (articulation). Recent phonetic research on speech errors has argued that multiple candidate sounds in phonological planning can influence articulation because the pronunciation of mis-selected error sounds is slightly skewed towards unselected target sounds. Yet research to date has only examined these phonetic distortions in experimentally-elicited errors, leaving doubt as to whether they reflect tendencies in spontaneous speech. Here, we analyzed the pronunciation of speech errors of English-speaking adults in natural conversations relative to matched correct words by the same speakers, and found the conjectured phonetic distortions. Comparison of these data with a larger set of experimentally-elicited errors failed to reveal significant differences between the two types of errors. These findings provide ecologically-valid data supporting models that allow for information about multiple planning representations to simultaneously influence speech articulation.

Prosody leaks into the memories of words

The average predictability (aka informativity) of a word in context has been shown to condition word duration (Seyfarth, 2014). All else being equal, words that tend to occur in more predictable environments are shorter than words that tend to occur in less predictable environments. One account of the informativity effect on duration is that the acoustic details of probabilistic reduction are stored as part of a word's mental representation. Other research has argued that predictability effects are tied to prosodic structure in integral ways. With the aim of assessing a potential prosodic basis for informativity effects in speech production, this study extends past work in two directions; it investigated informativity effects in another large language, Mandarin Chinese, and broadened the study beyond word duration to additional acoustic dimensions, pitch and intensity, known to index prosodic prominence. The acoustic information of content words was extracted from a large telephone conversation speech corpus with over 400,000 tokens and 6000 word types spoken by 1655 individuals and analyzed for the effect of informativity using frequency statistics estimated from a 431 million word subtitle corpus. Results indicated that words with low informativity have shorter durations, replicating the effect found in English. In addition, informativity had significant effects on maximum pitch and intensity, two phonetic dimensions related to prosodic prominence. Extending this interpretation, these results suggest that predictability is closely linked to prosodic prominence, and that the lexical representation of a word includes phonetic details associated with its average prosodic prominence in discourse. In other words, the lexicon absorbs prosodic influences on speech production.

Characterizing spoken responses in masked-onset priming of reading aloud using articulography

A key method for studying articulatory planning at different levels of phonological organization is masked-onset priming. In previous work using that paradigm the dependent variable has been acoustic response time (RT). We used electromagnetic articulography to measure articulatory RTs and the articulatory properties of speech gestures in non-word production in a masked-onset priming experiment. Initiation of articulation preceded acoustic response onset by 199 ms, but the acoustic lag varied by up to 63 ms, depending on the phonological structure of the target. Onset priming affected articulatory response latency, but had no effect on gestural duration, inter-gestural coordination, or articulatory velocity. This is consistent with an account of the masked-onset priming effect in which the computation from orthography of an abstract phonological representation of the target is initiated earlier in the primed than in the unprimed condition. We discuss the implications of these findings for models of speech production and the scope of articulatory planning and execution.

Maximum Speech Performance and Executive Control in Young Adult Speakers

Purpose This study investigated whether maximum speech performance, more specifically, the ability to rapidly alternate between similar syllables during speech production, is associated with executive control abilities in a nonclinical young adult population. Method Seventy-eight young adult participants completed two speech tasks, both operationalized as maximum performance tasks, to index their articulatory control: a diadochokinetic (DDK) task with nonword and real-word syllable sequences and a tongue-twister task. Additionally, participants completed three cognitive tasks, each covering one element of executive control (a Flanker interference task to index inhibitory control, a letter-number switching task to index cognitive switching, and an operation span task to index updating of working memory). Linear mixed-effects models were fitted to investigate how well maximum speech performance measures can be predicted by elements of executive control. Results Participants' cognitive switching ability was associated with their accuracy in both the DDK and tongue-twister speech tasks. Additionally, nonword DDK accuracy was more strongly associated with executive control than real-word DDK accuracy (which has to be interpreted with caution). None of the executive control abilities related to the maximum rates at which participants performed the two speech tasks. Conclusion These results underscore the association between maximum speech performance and executive control (cognitive switching in particular).

Talker-specific pronunciation or speech error? Discounting (or not) atypical pronunciations during speech perception

Perceptual recalibration allows listeners to adapt to talker-specific pronunciations, such as atypical realizations of specific sounds. Such recalibration can facilitate robust speech recognition. However, indiscriminate recalibration following any atypically pronounced words also risks interpreting pronunciations as characteristic of a talker that are in reality because of incidental, short-lived factors (such as a speech error). We investigate whether the mechanisms underlying perceptual recalibration involve inferences about the causes for unexpected pronunciations. In 5 experiments, we ask whether perceptual recalibration is blocked if the atypical pronunciations of an unfamiliar talker can also be attributed to other incidental causes. We investigated 3 type of incidental causes for atypical pronunciations: the talker is intoxicated, the talker speaks unusually fast, or the atypical pronunciations occur only in the context of tongue twisters. In all 5 experiments, we find robust evidence for perceptual recalibration, but little evidence that the presence of incidental causes block perceptual recalibration. We discuss these results in light of other recent findings that incidental causes can block perceptual recalibration. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The influence of lexical selection disruptions on articulation

Interactive models of language production predict that it should be possible to observe long-distance interactions; effects that arise at one level of processing influence multiple subsequent stages of representation and processing. We examine the hypothesis that disruptions arising in nonform-based levels of planning-specifically, lexical selection-should modulate articulatory processing. A novel automatic phonetic analysis method was used to examine productions in a paradigm yielding both general disruptions to formulation processes and, more specifically, overt errors during lexical selection. This analysis method allowed us to examine articulatory disruptions at multiple levels of analysis, from whole words to individual segments. Baseline performance by young adults was contrasted with young speakers' performance under time pressure (which previous work has argued increases interaction between planning and articulation) and performance by older adults (who may have difficulties inhibiting nontarget representations, leading to heightened interactive effects). The results revealed the presence of interactive effects. Our new analysis techniques revealed these effects were strongest in initial portions of responses, suggesting that speech is initiated as soon as the first segment has been planned. Interactive effects did not increase under response pressure, suggesting interaction between planning and articulation is relatively fixed. Unexpectedly, lexical selection disruptions appeared to yield some degree of facilitation in articulatory processing (possibly reflecting semantic facilitation of target retrieval) and older adults showed weaker, not stronger interactive effects (possibly reflecting weakened connections between lexical and form-level representations). (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Effects of Surprisal and Entropy on Vowel Duration in Japanese

Research on English and other languages has shown that syllables and words that contain more information tend to be produced with longer duration. This research is evolving into a general thesis that speakers articulate linguistic units with more information more robustly. While this hypothesis seems plausible from the perspective of communicative efficiency, previous support for it has come mainly from English and some other Indo-European languages. Moreover, most previous studies focus on global effects, such as the interaction of word duration and sentential/semantic predictability. The current study is focused at the level of phonotactics, exploring the effects of local predictability on vowel duration in Japanese, using the Corpus of Spontaneous Japanese. To examine gradient consonant-vowel phonotactics within a consonant-vowel-mora, consonant-conditioned Surprisal and Shannon Entropy were calculated, and their effects on vowel duration were examined, together with other linguistic factors that are known from previous research to affect vowel duration. Results show significant effects of both Surprisal and Entropy, as well as notable interactions with vowel length and vowel quality. The effect of Entropy is stronger on peripheral vowels than on central vowels. Surprisal has a stronger positive effect on short vowels than on long vowels. We interpret the main patterns and the interactions by conceptualizing Surprisal as an index of motor fluency and Entropy as an index of competition in vowel selection.

Towards the Quantification of Peggy Babcock: Speech Errors and Their Position within the Word

Sequences of similar (i.e., partially identical) words can be hard to say, as indicated by error frequencies, longer reaction and execution times. This study investigates the role of the location of this partial identity and the accompanying differences, i.e. whether errors are more frequent with mismatches in word onsets (top cop), codas (top tock) or both (pop tot). Number of syllables (tippy ticky) and empty positions (top ta) were also varied. Since the gradient nature of errors can be difficult to determine acoustically, articulatory data were investigated. Articulator movements were recorded using electromagnetic articulography, for up to 9 speakers of American English repeatedly producing 2-word sequences to an accelerating metronome. Most word pairs showed more intrusions and greater variability in coda than in onset position, in contrast to the predominance of onset position errors in corpora from perceptual observation.

Impaired Lexical Selection and Fluency in Post-Stroke Aphasia

BACKGROUND

Deficits in fluent language production are a hallmark of aphasia and may arise from impairments at different levels in the language system. It has been proposed that difficulty resolving lexical competition contributes to fluency deficits.

AIMS

The present study tested this hypothesis in a novel way: by examining whether narrative speech production fluency is associated with difficulty resolving lexical competition in spoken word recognition as measured by sensitivity to phonological neighborhood density.

METHODS & PROCEDURES

Nineteen participants with aphasia and 15 neurologically intact older adults identified spoken words that varied in phonological neighborhood density and were presented in moderate noise.

OUTCOMES & RESULTS

Neurologically intact participants exhibited the standard inhibitory effect of phonological neighborhood density on response times: slower recognition of spoken words from denser neighborhoods. Among participants with aphasia, the inhibitory effect of phonological neighborhood density (less accurate recognition of spoken words from denser neighborhoods) was smaller for participants with greater fluency. The neighborhood effect was larger for participants with greater receptive vocabulary knowledge, indicating that the fluency effect was not a result of general lexical deficits.

CONCLUSIONS

These results are consistent with the hypothesis that impaired lexical selection is a contributing factor in fluency deficits in post-stroke aphasia.

The difficulty of articulatory complexity

In our commentary, we offer some support for the view that frequency rather than a language-independent definition of complexity is a main factor determining speech production in healthy adults. We further discuss the limits of defining articulatory complexity based on transcription data. If we want to gauge the impact of substantive constraints on speech production, context-specific production dynamics should be considered, as has been underscored by articulatory-acoustic work on speech errors.

Variation in the speech signal as a window into the cognitive architecture of language production

The pronunciation of words is highly variable. This variation provides crucial information about the cognitive architecture of the language production system. This review summarizes key empirical findings about variation phenomena, integrating corpus, acoustic, articulatory, and chronometric data from phonetic and psycholinguistic studies. It examines how these data constrain our current understanding of word production processes and highlights major challenges and open issues that should be addressed in future research.

Identification and Remediation of Phonological and Motor Errors in Acquired Sound Production Impairment

Purpose

This study aimed to test whether an approach to distinguishing errors arising in phonological processing from those arising in motor planning also predicts the extent to which repetition-based training can lead to improved production of difficult sound sequences.

Method

Four individuals with acquired speech production impairment who produced consonant cluster errors involving deletion were examined using a repetition task. We compared the acoustic details of productions with deletion errors in target consonant clusters to singleton consonants. Changes in accuracy over the course of the study were also compared.

Results

Two individuals produced deletion errors consistent with a phonological locus of the errors, and 2 individuals produced errors consistent with a motoric locus of the errors. The 2 individuals who made phonologically driven errors showed no change in performance on a repetition training task, whereas the 2 individuals with motoric errors improved in their production of both trained and untrained items.

Conclusions

The results extend previous findings about a metric for identifying the source of sound production errors in individuals with both apraxia of speech and aphasia. In particular, this work may provide a tool for identifying predominant error types in individuals with complex deficits.

Electropalatography and its correlation to tongue movement ultrasonography in speech analysis

Purpose

To analyze the use of electropalatography and ultrasonography regarding speech therapy through literature narrative review.

Research strategies

A literature review was conducted at PubMed and Scielo databases, using descriptors as electropalatography, electropalatography AND evaluation, electropalatography AND therapy, electropalatography AND ultrasonography, electropalatography AND speech.

Selection criteria

The research criteria selected in the database were: studies in the past five years and studies in humans. In the pre-selection, studies that were duplicate, not fully available, and have shown no direct relation with electropalatography in speech-language therapy were discarded.

Data analysis

Data analysis was performed descriptively, following subdivisions: title, area, year, subject, implementation, and conclusion of the study.

Results

Twenty one papers were selected, eight of them using the term electropalatography, two with the keywords electropalatography AND evaluation, six with the keywords electropalatography AND therapy, three of them with the keywords electropalatography AND ultrasonography, and two papers with the keywords electropalatography AND speech.

Conclusion

Different types of research involving the use of electropalatography in the field of speech-language therapy were found and analyzed. Few researches have concomitantly used electropalatography and ultrasonography.

The Effect of Auditory Information on Patterns of Intrusions and Reductions

PURPOSE

The study investigates whether auditory information affects the nature of intrusion and reduction errors in reiterated speech. These errors are hypothesized to arise as a consequence of autonomous mechanisms to stabilize movement coordination. The specific question addressed is whether this process is affected by auditory information so that it will influence the occurrence of intrusions and reductions.

METHODS

Fifteen speakers produced word pairs with alternating onset consonants and identical rhymes repetitively at a normal and fast speaking rate, in masked and unmasked speech. Movement ranges of the tongue tip, tongue dorsum, and lower lip during onset consonants were retrieved from kinematic data collected with electromagnetic articulography. Reductions and intrusions were defined as statistical outliers from movement range distributions of target and nontarget articulators, respectively.

RESULTS

Regardless of masking condition, the number of intrusions and reductions increased during the course of a trial, suggesting movement stabilization. However, compared with unmasked speech, speakers made fewer intrusions in masked speech. The number of reductions was not significantly affected.

CONCLUSIONS

Masking of auditory information resulted in fewer intrusions, suggesting that speakers were able to pay closer attention to their articulatory movements. This highlights a possible stabilizing role for proprioceptive information in speech movement coordination.

Phonetic basis of phonemic paraphasias in aphasia: Evidence for cascading activation

Phonemic paraphasias are a common presenting symptom in aphasia and are thought to reflect a deficit in which selecting an incorrect phonemic segment results in the clear-cut substitution of one phonemic segment for another. The current study re-examines the basis of these paraphasias. Seven left hemisphere-damaged aphasics with a range of left hemisphere lesions and clinical diagnoses including Broca's, Conduction, and Wernicke's aphasia, were asked to produce syllable-initial voiced and voiceless fricative consonants, [z] and [s], in CV syllables followed by one of five vowels [i e a o u] in isolation and in a carrier phrase. Acoustic analyses were conducted focusing on two acoustic parameters signaling voicing in fricative consonants: duration and amplitude properties of the fricative noise. Results show that for all participants, regardless of clinical diagnosis or lesion site, phonemic paraphasias leave an acoustic trace of the original target in the error production. These findings challenge the view that phonemic paraphasias arise from a mis-selection of phonemic units followed by its correct implementation, as traditionally proposed. Rather, they appear to derive from a common mechanism with speech errors reflecting the co-activation of a target and competitor resulting in speech output that has some phonetic properties of both segments.

Automatic analysis of slips of the tongue: Insights into the cognitive architecture of speech production

Traces of the cognitive mechanisms underlying speaking can be found within subtle variations in how we pronounce sounds. While speech errors have traditionally been seen as categorical substitutions of one sound for another, acoustic/articulatory analyses show they partially reflect the intended sound. When "pig" is mispronounced as "big," the resulting /b/ sound differs from correct productions of "big," moving towards intended "pig"-revealing the role of graded sound representations in speech production. Investigating the origins of such phenomena requires detailed estimation of speech sound distributions; this has been hampered by reliance on subjective, labor-intensive manual annotation. Computational methods can address these issues by providing for objective, automatic measurements. We develop a novel high-precision computational approach, based on a set of machine learning algorithms, for measurement of elicited speech. The algorithms are trained on existing manually labeled data to detect and locate linguistically relevant acoustic properties with high accuracy. Our approach is robust, is designed to handle mis-productions, and overall matches the performance of expert coders. It allows us to analyze a very large dataset of speech errors (containing far more errors than the total in the existing literature), illuminating properties of speech sound distributions previously impossible to reliably observe. We argue that this provides novel evidence that two sources both contribute to deviations in speech errors: planning processes specifying the targets of articulation and articulatory processes specifying the motor movements that execute this plan. These findings illustrate how a much richer picture of speech provides an opportunity to gain novel insights into language processing.

Phonological Encoding in Mandarin Chinese: Evidence from Tongue Twisters

Models of connected speech production in Mandarin Chinese must specify how lexical tone, speech segments, and phrase-level prosody are integrated in speech production. This study used tongue twisters to test predictions of the two different models of word form encoding. Tongue twisters were constructed from 5 sets of characters that rotated pairs of initial segments or pairs of tones, or both, across format (ABAB, ABBA), and across position of the characters in four-character tongue twister strings. Fifty two native Mandarin Chinese speakers read aloud 120 tongue twisters, repeating each one six times in a row. They made a total of 3503 (2.34%) segment errors and 1372 (.92%) tone errors. Segment errors occurred on the onsets of the first and third characters in the ABBA but not ABAB segment-alternating tongue twisters, and on the onsets of the second and fourth characters of the tone-alternating tongue twisters. Tone errors were highest on the third and fourth characters in the tone-alternating tongue twisters. The pattern of tone errors is consistent with the claim that tone is associated to a metrical frame prior to segment encoding, while the format by position interaction found for the segment-alternating tongue twisters suggest articulatory gestures oscillate in segment production as proposed by gestural phonology.

Lexical frequency effects on articulation: a comparison of picture naming and reading aloud

The present study investigated whether lexical frequency, a variable that is known to affect the time taken to utter a verbal response, may also influence articulation. Pairs of words that differed in terms of their relative frequency, but were matched on their onset, vowel, and number of phonemes (e.g., map vs. mat, where the former is more frequent than the latter) were used in a picture naming and a reading aloud task. Low-frequency items yielded slower response latencies than high-frequency items in both tasks, with the frequency effect being significantly larger in picture naming compared to reading aloud. Also, initial-phoneme durations were longer for low-frequency items than for high-frequency items. The frequency effect on initial-phoneme durations was slightly more prominent in picture naming than in reading aloud, yet its size was very small, thus preventing us from concluding that lexical frequency exerts an influence on articulation. Additionally, initial-phoneme and whole-word durations were significantly longer in reading aloud compared to picture naming. We discuss our findings in the context of current theories of reading aloud and speech production, and the approaches they adopt in relation to the nature of information flow (staged vs. cascaded) between cognitive and articulatory levels of processing.

A trade-off between somatosensory and auditory related brain activity during object naming but not reading

The parietal operculum, particularly the cytoarchitectonic area OP1 of the secondary somatosensory area (SII), is involved in somatosensory feedback. Using fMRI with 58 human subjects, we investigated task-dependent differences in SII/OP1 activity during three familiar speech production tasks: object naming, reading and repeatedly saying "1-2-3." Bilateral SII/OP1 was significantly suppressed (relative to rest) during object naming, to a lesser extent when repeatedly saying "1-2-3" and not at all during reading. These results cannot be explained by task difficulty but the contrasting difference between naming and reading illustrates how the demands on somatosensory activity change with task, even when motor output (i.e., production of object names) is matched. To investigate what determined SII/OP1 deactivation during object naming, we searched the whole brain for areas where activity increased as that in SII/OP1 decreased. This across subject covariance analysis revealed a region in the right superior temporal sulcus (STS) that lies within the auditory cortex, and is activated by auditory feedback during speech production. The tradeoff between activity in SII/OP1 and STS was not observed during reading, which showed significantly more activation than naming in both SII/OP1 and STS bilaterally. These findings suggest that, although object naming is more error prone than reading, subjects can afford to rely more or less on somatosensory or auditory feedback during naming. In contrast, fast and efficient error-free reading places more consistent demands on both types of feedback, perhaps because of the potential for increased competition between lexical and sublexical codes at the articulatory level.

How much is a word? Predicting ease of articulation planning from apraxic speech error patterns

BACKGROUND

According to intuitive concepts, 'ease of articulation' is influenced by factors like word length or the presence of consonant clusters in an utterance. Imaging studies of speech motor control use these factors to systematically tax the speech motor system. Evidence from apraxia of speech, a disorder supposed to result from speech motor planning impairment after lesions to speech motor centers in the left hemisphere, supports the relevance of these and other factors in disordered speech planning and the genesis of apraxic speech errors. Yet, there is no unified account of the structural properties rendering a word easy or difficult to pronounce.

AIM

To model the motor planning demands of word articulation by a nonlinear regression model trained to predict the likelihood of accurate word production in apraxia of speech.

METHOD

We used a tree-structure model in which vocal tract gestures are embedded in hierarchically nested prosodic domains to derive a recursive set of terms for the computation of the likelihood of accurate word production. The model was trained with accuracy data from a set of 136 words averaged over 66 samples from apraxic speakers. In a second step, the model coefficients were used to predict a test dataset of accuracy values for 96 new words, averaged over 120 samples produced by a different group of apraxic speakers.

RESULTS

Accurate modeling of the first dataset was achieved in the training study (R(2)adj = .71). In the cross-validation, the test dataset was predicted with a high accuracy as well (R(2)adj = .67). The model shape, as reflected by the coefficient estimates, was consistent with current phonetic theories and with clinical evidence. In accordance with phonetic and psycholinguistic work, a strong influence of word stress on articulation errors was found.

CONCLUSIONS

The proposed model provides a unified and transparent account of the motor planning requirements of word articulation.

Accommodation of end-state comfort reveals subphonemic planning in speech

Applying the 'end-state comfort' hypothesis of Rosenbaum et al. [J Exp Psych Learn Mem Cogn 1992;18:1058; Acta Psychol (Amst) 1996;94:59] to tongue motion provides evidence of long-distance subphonemic planning in speech. Speakers' tongue postures may anticipate upcoming speech up to three segments, two syllables, and a morpheme or word boundary later. We used M-mode ultrasound imaging to measure the direction of tongue tip/blade movements for known variants of flap/tap allophones of North American English /t/ and /d/. Results show that speakers produce different flap variants early in words or word sequences so as to facilitate the kinematic needs of flap/tap or other /r/ variants that appear later in the word or word sequence. Similar results were also observed across word boundaries, indicating that this is not a lexical effect.

Ultrasound applicability in Speech Language Pathology and Audiology

PURPOSE: To present recent studies that used the ultrasound in the fields of Speech Language Pathology and Audiology, which evidence possibilities of the applicability of this technique in different subareas. RESEARCH STRATEGY: A bibliographic research was carried out in the PubMed database, using the keywords "ultrasonic," "speech," "phonetics," "Speech, Language and Hearing Sciences," "voice," "deglutition," and "myofunctional therapy," comprising some areas of Speech Language Pathology and Audiology Sciences. The keywords "ultrasound," "ultrasonography," "swallow," "orofacial myofunctional therapy," and "orofacial myology" were also used in the search. SELECTION CRITERIA: Studies in humans from the past 5 years were selected. In the preselection, duplicated studies, articles not fully available, and those that did not present direct relation between ultrasound and Speech Language Pathology and Audiology Sciences were discarded. DATA ANALYSIS: The data were analyzed descriptively and classified subareas of Speech Language Pathology and Audiology Sciences. The following items were considered: purposes, participants, procedures, and results. RESULTS: We selected 12 articles for ultrasound versus speech/phonetics subarea, 5 for ultrasound versus voice, 1 for ultrasound versus muscles of mastication, and 10 for ultrasound versus swallow. Studies relating "ultrasound" and "Speech Language Pathology and Audiology Sciences" in the past 5 years were not found. CONCLUSION: Different studies on the use of ultrasound in Speech Language Pathology and Audiology Sciences were found. Each of them, according to its purpose, confirms new possibilities of the use of this instrument in the several subareas, aiming at a more accurate diagnosis and new evaluative and therapeutic possibilities.

Production of tongue twisters by speakers with partial glossectomy

Abstract A partial glossectomy can affect speech production. The goal of this study was to investigate the effect of the presence of a tumour as well as the glossectomy surgery on the patients' production of tongue twisters with the sounds [t] and [k]. Fifteen patients with tongue cancer and 10 healthy controls took part in the study. The outcome measures were the patients' speech acceptability, rate of errors, the time needed to produce the tongue twisters, pause duration between item repetitions and the tongue shape during the production of the consonants [t] and [k] before and after surgery. The patients' speech acceptability deteriorated after the surgery. Compared to controls, the patients' productions of the tongue twisters were slower but not more errorful. Following the surgery, their speed of production did not change, but the rate of errors was higher. Pause duration between items was longer in the patients than in the controls but did not increase from before to after surgery. Analysis of the patients' tongue shapes for the productions of [t] and [k] indicated a higher elevation following the surgery for the patients with flap reconstructions. The results demonstrated that the surgical resection of the tongue changed the error rate but not the speed of production for the patient. The differences in pause duration also indicate that the tumour and the surgical resection of the tongue may impact the phonological planning of the tongue twister.

A comparison of two procedures for verbal response time fractionation

To describe the mental architecture between stimulus and response, cognitive models often divide the stimulus-response (SR) interval into stages or modules. Predictions derived from such models are typically tested by focusing on the moment of response emission, through the analysis of response time (RT) distributions. To go beyond the single response event, we recently proposed a method to fractionate verbal RTs into two physiologically defined intervals that are assumed to reflect different processing stages. The analysis of the durations of these intervals can be used to study the interaction between cognitive and motor processing during speech production. Our method is inspired by studies on decision making that used manual responses, in which RTs were fractionated into a premotor time (PMT), assumed to reflect cognitive processing, and a motor time (MT), assumed to reflect motor processing. In these studies, surface EMG activity was recorded from participants' response fingers. EMG onsets, reflecting the initiation of a motor response, were used as the point of fractionation. We adapted this method to speech-production research by measuring verbal responses in combination with EMG activity from facial muscles involved in articulation. However, in contrast to button-press tasks, the complex task of producing speech often resulted in multiple EMG bursts within the SR interval. This observation forced us to decide how to operationalize the point of fractionation: as the first EMG burst after stimulus onset (the stimulus-locked approach), or as the EMG burst that is coupled to the vocal response (the response-locked approach). The point of fractionation has direct consequences on how much of the overall task effect is captured by either interval. Therefore, the purpose of the current paper was to compare both onset-detection procedures in order to make an informed decision about which of the two is preferable. We concluded in favor or the response-locked approach.

Voice onset time in consonant cluster errors: can phonetic accommodation differentiate cognitive from motor errors?

PURPOSE

Phonetic accommodation in speech errors has traditionally been used to identify the processing level at which an error has occurred. Recent studies have challenged the view that noncanonical productions may solely be due to phonetic, not phonological, processing irregularities, as previously assumed. The authors of the present study investigated the relationship between phonological and phonetic planning processes on the basis of voice onset time (VOT) behavior in consonant cluster errors.

METHOD

Acoustic data from 22 German speakers were recorded while eliciting errors on sibilant-stop clusters. Analyses consider VOT duration as well as intensity and spectral properties of the sibilant.

RESULTS

Of all incorrect responses, 28% failed to show accommodation. Sibilant intensity and spectral properties differed from correct responses irrespective of whether VOT was accommodated.

CONCLUSIONS

The data overall do not allow using (a lack of) accommodation as a diagnostic as to the processing level at which an error has occurred. The data support speech production models that allow for an integrated view of phonological and phonetic processing.

Self-, other-, and joint monitoring using forward models

In the psychology of language, most accounts of self-monitoring assume that it is based on comprehension. Here we outline and develop the alternative account proposed by Pickering and Garrod (2013), in which speakers construct forward models of their upcoming utterances and compare them with the utterance as they produce them. We propose that speakers compute inverse models derived from the discrepancy (error) between the utterance and the predicted utterance and use that to modify their production command or (occasionally) begin anew. We then propose that comprehenders monitor other people’s speech by simulating their utterances using covert imitation and forward models, and then comparing those forward models with what they hear. They use the discrepancy to compute inverse models and modify their representation of the speaker’s production command, or realize that their representation is incorrect and may develop a new production command. We then discuss monitoring in dialogue, paying attention to sequential contributions, concurrent feedback, and the relationship between monitoring and alignment.

The effect of phonetic context on speech movements in repetitive speech

This study examined how, in repetitive speech, articulatory movements differ in degree of variability and movement range depending on articulatory constraints manipulated by phonetic context and type of CVC-CVC word pair. These pairs consisted of words that either differed in onset consonants but shared rhymes, or were identical. Articulatory constraints were manipulated by employing different combinations of vowels and consonants. The word pairs were produced in a repetitive speech task at a normal and fast speaking rate. Articulatory movements were measured with 3D electro-magnetic articulography. As measures of variability, median movement ranges and the coefficient of variation of target and non-target articulators were determined. To assess possible biomechanical constraints, correlation values between target and simultaneous non-target articulators were calculated as well. The results revealed that word pairs with different onsets had larger movement ranges than word pairs with identical onsets. In identical word pairs, the coefficient of variation showed higher values in the second than in the first word. This difference was not present in the alternating onset word pairs. For both types of word pairs, higher speaking rates showed higher correlations between target and non-target articulators than lower speaking rates, suggesting stronger biomechanical constraints for the former condition.

"If two witches would watch two watches, which witch would watch which watch?" tDCS over the left frontal region modulates tongue twister repetition in healthy subjects

Recent studies have demonstrated that transcranial direct current stimulation (tDCS) modulates cortical activity in the human brain. In the language domain, it has already been shown that during a naming task tDCS reduces vocal reaction times in healthy individuals and speeds up the recovery process in left brain-damaged aphasic subjects. In this study, we wondered whether tDCS would influence the ability to articulate tongue twisters during a repetition task. Three groups of 10 healthy individuals were asked to repeat a list of tongue twisters in three different stimulation conditions: one group performed the task during anodal tDCS (atDCS) (20 min, 2 mA) over the left frontal region; a second group during cathodal tDCS delivered over the same region; and, in a third group, sham stimulation was applied. Accuracy and vocal reaction times in repeating each tongue twister before, during and 1h after the stimulation were recorded. Participants were more accurate and faster at repeating the stimuli during atDCS than at baseline, while cathodal tDCS significantly reduced their performance in terms of accuracy and reaction times. No significant differences were observed among the three time points during the sham condition. We believe that these data clearly confirm that the left frontal region is critically involved in the process of speech repetition. They are also in line with recent evidence suggesting that frontal tDCS might be used as a therapeutic tool in patients suffering from articulatory deficits.

Phonological and motor errors in individuals with acquired sound production impairment

PURPOSE

This study aimed to compare sound production errors arising due to phonological processing impairment with errors arising due to motor speech impairment.

METHOD

Two speakers with similar clinical profiles who produced similar consonant cluster simplification errors were examined using a repetition task. We compared both overall accuracy and acoustic details of hundreds of productions with target consonant clusters to tokens with singletons. Changes in accuracy over the course of the study were also compared.

RESULTS

In target words with consonant cluster simplification, the individual whose errors reflected phonological impairment produced articulatory timing consistent with singleton onsets. These productions improved when resyllabification was possible, but error rates were not affected by exposure. In contrast, the individual with motoric-based errors produced simplifications that contained the articulatory timing associated with clusters. Accuracy was not affected by the ability to resyllabify, but it did significantly improve following repeated production.

CONCLUSIONS

Our findings reveal clear differences between errors arising in phonological processing and in motor planning that reflect the underlying systems. The changes over the course of the study suggest that error types with different sources are responsive to different intervention strategies.

Patterns of impairments in AOS and mechanisms of interaction between phonological and phonetic encoding

PURPOSE

One reason why the diagnosis of apraxia of speech (AOS) and its underlying impairment are often debated may lie in the fact that most patients do not display pure patterns of AOS. Mixed patterns are clearly acknowledged at other levels of impairment (e.g., lexical-semantic and lexical-phonological), and they have contributed to debate about the degree of interaction between encoding levels; by contrast, mixed impairments and mechanisms of interaction are less acknowledged at the levels of phonological and phonetic processes. Here, the author aims at bringing together empirical evidence in favor of an interaction between phonological and phonetic encoding and of the predominance of mixed patterns of impairment over pure phonetic impairment.

METHOD

The author reviews empirical results from acoustic and psycholinguistic studies, both with healthy speakers and speakers with brain damage, favoring independent phonological and phonetic encoding and separable impairments as well as recent research pointing to an interaction between phonological and phonetic encoding processes and overlapping patterns of impairments.

CONCLUSIONS

Acknowledging interaction between phonological and phonetic processing has clear consequences on the definition of patterns of impairment. In particular, phonetic errors have not necessarily a phonetic origin, and most patterns of impairment are bound to display both phonological and phonetic features.

Interaction and representational integration: evidence from speech errors

We examine the mechanisms that support interaction between lexical, phonological and phonetic processes during language production. Studies of the phonetics of speech errors have provided evidence that partially activated lexical and phonological representations influence phonetic processing. We examine how these interactive effects are modulated by lexical frequency. Previous research has demonstrated that during lexical access, the processing of high frequency words is facilitated; in contrast, during phonetic encoding, the properties of low frequency words are enhanced. These contrasting effects provide the opportunity to distinguish two theoretical perspectives on how interaction between processing levels can be increased. A theory in which cascading activation is used to increase interaction predicts that the facilitation of high frequency words will enhance their influence on the phonetic properties of speech errors. Alternatively, if interaction is increased by integrating levels of representation, the phonetics of speech errors will reflect the retrieval of enhanced phonetic properties for low frequency words. Utilizing a novel statistical analysis method, we show that in experimentally induced speech errors low lexical frequency targets and outcomes exhibit enhanced phonetic processing. We sketch an interactive model of lexical, phonological and phonetic processing that accounts for the conflicting effects of lexical frequency on lexical access and phonetic processing.