Status of prosody in the practices of speech-language pathologists in France: A survey on theoretical and clinical dimensions

PURPOSE

Many populations in the scope of speech and language pathologists (SLPs) are at risk of prosodic disorders that can impact communicative ability. While a few studies have examined the importance of prosody in the clinical practice of English-speaking SLPs, there is a lack of similar research in non-English-speaking countries. The current study aimed to establish an overview of the situation in France and to determine factors that might be associated with assessing and treating prosody.

METHOD

We collected data about the theoretical and clinical dimensions related to prosody from SLPs in France using an online survey.

RESULTS

One hundred and twenty-eight valid responses were analyzed. Results suggest that both emotional and linguistic prosodies are examined by SLPs. Some aspects of prosody seem to be mastered better than others. While they are aware of the major prosodic difficulties in various pathologies and their negative impact, most SLPs in France rarely or never assess prosody. They feel more uncomfortable with it than with other speech-language domains and often do not consider it as a therapeutic target. Importantly, the perception of prosody as a therapeutic tool is associated with the frequency of assessing and addressing prosodic impairment.

CONCLUSIONS

Further studies should focus on identifying the factors that could improve practices and developing comprehensive assessment tools and evidence-based intervention methods in French. Providing better training in prosody and setting up more collaborations between SLPs and researchers in linguistics and psycholinguistics would be keys in developing this field.

Brain responses to lexical attestedness and phonological well-formedness as revealed by fast periodic visual stimulation

We investigated the mechanisms underlying the online-processing of phonological constraints using oddball fast-periodic visual stimulation coupled with EEG. We focused on the Sonority Sequencing Principle and examined whether steady-state visual evoked potentials (SSVEPs) are sensitive to the sonority constraint on syllable onsets. Native French speakers were presented with streams of CCVC non-words (C: consonant, V: vowel) at a fixed 6-Hz base rate. We manipulated the phonological well-formedness and lexical attestedness of CC onsets in two conditions. SSVPs were observed at the base rate associated to visual stimuli. As expected, they did not differ between conditions. Oddball SSVEPs were observed at 1.2 Hz (and its harmonics) and differed in the two conditions. These results showed that SSVEPs are sensitive to sublexical features. They also suggest that the processing of phonological constraints rely on mechanisms which could be dissociated from those underlying the processing of statistical properties of the lexicon.

Visual prediction cues can facilitate behavioural and neural speech processing in young and older adults

The ability to process speech evolves over the course of the lifespan. Understanding speech at low acoustic intensity and in the presence of background noise becomes harder, and the ability for older adults to benefit from audiovisual speech also appears to decline. These difficulties can have important consequences on quality of life. Yet, a consensus on the cause of these difficulties is still lacking. The objective of this study was to examine the processing of speech in young and older adults under different modalities (i.e. auditory [A], visual [V], audiovisual [AV]) and in the presence of different visual prediction cues (i.e., no predictive cue (control), temporal predictive cue, phonetic predictive cue, and combined temporal and phonetic predictive cues). We focused on recognition accuracy and four auditory evoked potential (AEP) components: P1-N1-P2 and N2. Thirty-four right-handed French-speaking adults were recruited, including 17 younger adults (28 ± 2 years; 20-42 years) and 17 older adults (67 ± 3.77 years; 60-73 years). Participants completed a forced-choice speech identification task. The main findings of the study are: (1) The faciliatory effect of visual information was reduced, but present, in older compared to younger adults, (2) visual predictive cues facilitated speech recognition in younger and older adults alike, (3) age differences in AEPs were localized to later components (P2 and N2), suggesting that aging predominantly affects higher-order cortical processes related to speech processing rather than lower-level auditory processes. (4) Specifically, AV facilitation on P2 amplitude was lower in older adults, there was a reduced effect of the temporal predictive cue on N2 amplitude for older compared to younger adults, and P2 and N2 latencies were longer for older adults. Finally (5) behavioural performance was associated with P2 amplitude in older adults. Our results indicate that aging affects speech processing at multiple levels, including audiovisual integration (P2) and auditory attentional processes (N2). These findings have important implications for understanding barriers to communication in older ages, as well as for the development of compensation strategies for those with speech processing difficulties.

Parkinson's disease impacts feedback production during verbal communication

BACKGROUND

Parkinson's disease (PD) leads to changes in verbal communications. The focus of most studies to date has been on speech impairment, which is specifically referred to as dysarthria. Although these studies are crucial to understanding the impact of PD on verbal communication, they do not focus on the features of dialogues between people with PD (PwPD) and other people in communicative contexts.

AIMS

To investigate whether PwPD produce less feedback than typical people during dialogue, thus potentially making it more difficult for them to reach mutual comprehension (i.e., common ground) with their conversational partner.

METHODS & PROCEDURES

A matching task experiment was conducted during which an experimenter described abstract pictures to a participant, who was either a PwPD or a typical participant, so that he or she could organize these pictures in a grid. The participants could produce as much feedback as they liked.

OUTCOMES & RESULTS

PwPD were less likely to produce feedback than typical participants. This effect was mainly driven by two specific types of feedback: acknowledgment tokens and hesitations.

CONCLUSIONS & IMPLICATIONS

The results suggest that PD impacts feedback production. This could decrease the communicative abilities of PwPD in interactive contexts by affecting grounding, that is, the ability to build common ground with others. This paper is one of the first to specifically document the production of feedback markers in PwPD. Future studies should examine the extent to which our results, which were obtained in a controlled dialogue task, may be generalized to daily-life conversions. From a clinical perspective, our study points to the necessity of assessing feedback production, and more generally abilities related to common ground construction and use, during PD progression.

WHAT IS ALREADY KNOWN ON THE SUBJECT

A few studies to date have analyzed conversational interactions between people with Parkinson's disease (PwPD) and others. The main focus is usually on potential difficulties of PwPD and their partners during the interaction and the strategies adopted to "repair" these problems. Another important feature of any interaction is the production of feedback. Feedback production plays a key role in building and using common ground to ensure mutual comprehension between interlocutors. The impact of Parkinson's disease on feedback production has received little attention in the literature to date.

WHAT THIS STUDY ADDS

The purpose of this study was to compare feedback production in a dialogue task (i.e., goal-oriented interaction) in PwPD versus typical controls. Our results revealed that PwPD produced less feedback for their dialogue partners than did typical participants. This effect was mainly driven by two specific types of feedback: acknowledgment tokens and hesitations. This paper is one of the firsts to specifically document the production of feedback markers in PwPD and to illustrate that PwPD and their dialogue partners may require more time and effort to establish common ground.

CLINICAL IMPLICATIONS OF THIS STUDY

Our findings suggest that an appropriate evaluation of feedback production by speech and language therapists, as well the management of potential deficits, would be beneficial. More broadly, we believe that the evaluation and management of PwPD should take into account the theoretical framework used in this study, in particular the role of common ground in communication.

Word segmentation based on prosody in Parkinson's Disease

While Parkinson's Disease (PD) impacts the production of prosody and may lead to dysprosody, its effect on the perception of prosody is less clear. In the current study, we investigated how people with PD (PwPD) segment continuous speech using prosodic cues. We used phonemically identical and prosodically different sequences in French. Twenty-three PwPD and 30 controls took part in the study. PwPD showed similar performance to controls (mean difference in terms of correct responses = 2%, 95% confidence interval = [-4%; 8%]). Using Bayesian statistics, our data is 3.6 times more in favour of the null model compared to the alternative model (i.e. difference between PwPD and controls). It thus seems unlikely that PD impacts the perception of prosody systematically. Furthermore, the cognitive performance of PwPD predicted their performance in our segmentation task. This suggests interesting pathways for future research on the mechanisms underlying the impact of PD on speech processing. Clinically, our findings suggest that adequate evaluation of the cognitive capacity of PwPD would help speech and language therapists in assessing speech processing skills in PwPD and in managing their speech impairments.

Synesthesia in children with difficulties in written language learning

We tested whether the acquisition of grapheme-color synesthesia during childhood is related to difficulties in written language learning by measuring whether it is more frequent in 79 children receiving speech and language therapy for such difficulties than in the general population of children (1.3%). By using criteria as similar as possible to those used in the reference study (Simner et al., 2009), we did not identify any synesthete (Bayesian 95% credible interval [0, 4.5]% for a flat prior). The odds of the null model (no difference between 0/79 and 1.3%) over alternative models is 28 (Bayes Factor). A higher prevalence of grapheme-color synesthetes among children with learning difficulties is therefore very unlikely, questioning the hypothesis of a link between synesthesia and difficulties in language acquisition. We also describe the difficulty of diagnosing synesthesia in children and discuss the need for new approaches to do so.

Audiovisual speech segmentation in post-stroke aphasia: a pilot study

Background: Stroke may cause sentence comprehension disorders. Speech segmentation, i.e. the ability to detect word boundaries while listening to continuous speech, is an initial step allowing the successful identification of words and the accurate understanding of meaning within sentences. It has received little attention in people with post-stroke aphasia (PWA).Objectives: Our goal was to study speech segmentation in PWA and examine the potential benefit of seeing the speakers' articulatory gestures while segmenting sentences.Methods: Fourteen PWA and twelve healthy controls participated in this pilot study. Performance was measured with a word-monitoring task. In the auditory-only modality, participants were presented with auditory-only stimuli while in the audiovisual modality, visual speech cues (i.e. speaker's articulatory gestures) accompanied the auditory input. The proportion of correct responses was calculated for each participant and each modality. Visual enhancement was then calculated in order to estimate the potential benefit of seeing the speaker's articulatory gestures.Results: Both in auditory-only and audiovisual modalities, PWA performed significantly less well than controls, who had 100% correct performance in both modalities. The performance of PWA was correlated with their phonological ability. Six PWA used the visual cues. Group level analysis performed on PWA did not show any reliable difference between the auditory-only and audiovisual modalities (median of visual enhancement = 7% [Q1 - Q3: -5 - 39]).Conclusion: Our findings show that speech segmentation disorder may exist in PWA. This points to the importance of assessing and training speech segmentation after stroke. Further studies should investigate the characteristics of PWA who use visual speech cues during sentence processing.

Word segmentation in phonemically identical and prosodically different sequences using cochlear implants: A case study

Cochlear implant (CI) users frequently achieve good speech understanding based on phoneme and word recognition. However, there is a significant variability between CI users in processing prosody. The aim of this study was to examine the abilities of an excellent CI user to segment continuous speech using intonational cues. A post-lingually deafened adult CI user and 22 normal hearing (NH) subjects segmented phonemically identical and prosodically different sequences in French such as 'l'affiche' (the poster) versus 'la fiche' (the sheet), both [lafiʃ]. All participants also completed a minimal pair discrimination task. Stimuli were presented in auditory-only and audiovisual presentation modalities. The performance of the CI user in the minimal pair discrimination task was 97% in the auditory-only and 100% in the audiovisual condition. In the segmentation task, contrary to the NH participants, the performance of the CI user did not differ from the chance level. Visual speech did not improve word segmentation. This result suggests that word segmentation based on intonational cues is challenging when using CIs even when phoneme/word recognition is very well rehabilitated. This finding points to the importance of the assessment of CI users' skills in prosody processing and the need for specific interventions focusing on this aspect of speech communication.

High-frequency neural activity predicts word parsing in ambiguous speech streams

During speech listening, the brain parses a continuous acoustic stream of information into computational units (e.g., syllables or words) necessary for speech comprehension. Recent neuroscientific hypotheses have proposed that neural oscillations contribute to speech parsing, but whether they do so on the basis of acoustic cues (bottom-up acoustic parsing) or as a function of available linguistic representations (top-down linguistic parsing) is unknown. In this magnetoencephalography study, we contrasted acoustic and linguistic parsing using bistable speech sequences. While listening to the speech sequences, participants were asked to maintain one of the two possible speech percepts through volitional control. We predicted that the tracking of speech dynamics by neural oscillations would not only follow the acoustic properties but also shift in time according to the participant's conscious speech percept. Our results show that the latency of high-frequency activity (specifically, beta and gamma bands) varied as a function of the perceptual report. In contrast, the phase of low-frequency oscillations was not strongly affected by top-down control. Whereas changes in low-frequency neural oscillations were compatible with the encoding of prelexical segmentation cues, high-frequency activity specifically informed on an individual's conscious speech percept.

A hierarchy of cortical responses to sequence violations in three-month-old infants

The adult human brain quickly adapts to regular temporal sequences, and emits a sequence of novelty responses when these regularities are violated. These novelty responses have been interpreted as error signals that reflect the difference between the incoming signal and predictions generated at multiple cortical levels. Do infants already possess such a hierarchy of violation-detection mechanisms? Using high-density recordings of event-related potentials during an auditory local-global violation paradigm, we show that three-month-old infants process novelty in temporal sequences at two distinct levels. Violations of local expectancies, such as perceiving a deviant vowel "a" after repeated presentation of another vowel i-i-i, elicited an early auditory mismatch response. Conversely, violations of global expectancies, such as hearing the rare sequence a-a-a-a instead of the frequent sequence a-a-a-i, modulated this early mismatch response and led to a late frontal negative slow wave, whose cortical sources included the left inferior frontal region. These results suggest that the infant brain already possesses two dissociable systems for temporal sequence learning.

Perceptuo-motor interactions in the perceptual organization of speech: evidence from the verbal transformation effect

The verbal transformation effect (VTE) refers to perceptual switches while listening to a speech sound repeated rapidly and continuously. It is a specific case of perceptual multistability providing a rich paradigm for studying the processes underlying the perceptual organization of speech. While the VTE has been mainly considered as a purely auditory effect, this paper presents a review of recent behavioural and neuroimaging studies investigating the role of perceptuo-motor interactions in the effect. Behavioural data show that articulatory constraints and visual information from the speaker's articulatory gestures can influence verbal transformations. In line with these data, functional magnetic resonance imaging and intracranial electroencephalography studies demonstrate that articulatory-based representations play a key role in the emergence and the stabilization of speech percepts during a verbal transformation task. Overall, these results suggest that perceptuo (multisensory)-motor processes are involved in the perceptual organization of speech and the formation of speech perceptual objects.