Cross-Language Transfer and Attentional Control in Early Bilingual Speech

Purpose: This study investigated the roles of cross-language transfer of first language (L1) and attentional control in second-language (L2) speech perception and production of sequential bilinguals, taking phonological overlap into account. Method: Twenty-five monolingual Dutch-speaking and 25 sequential bilingual Turkish–Dutch-speaking 3- and 4-year-olds were tested using picture identification tasks for speech perception in L1 Turkish and L2 Dutch, single-word tasks for speech production in L1 and L2, and a visual search task for attentional control. Phonological overlap was manipulated by dividing the speech tasks into subsets of phonemes that were either shared or unshared between languages. Results: In Dutch speech perception and production, monolingual children obtained higher accuracies than bilingual peers. Bilinguals showed equal performance in L1 and L2 perception but scored higher on L1 than on L2 production. For speech perception of shared phonemes, linear regression analyses revealed no direct effects of attention and L1 on L2. For speech production of shared phonemes, attention and L1 directly affected L2. When exploring unshared phonemes, direct effects of attentional control on L2 were demonstrated not only for speech production but also for speech perception. Conclusions: The roles of attentional control and cross-language transfer on L2 speech are different for shared and unshared phonemes. Whereas L2 speech production of shared phonemes is also supported by cross-language transfer of L1, L2 speech perception and production of unshared phonemes benefit from attentional control only. This underscores the clinical importance of considering phonological overlap and supporting attentional control when assisting young sequential bilinguals' L2 development.

Imagined speech can be decoded from low- and cross-frequency intracranial EEG features

Reconstructing intended speech from neural activity using brain-computer interfaces holds great promises for people with severe speech production deficits. While decoding overt speech has progressed, decoding imagined speech has met limited success, mainly because the associated neural signals are weak and variable compared to overt speech, hence difficult to decode by learning algorithms. We obtained three electrocorticography datasets from 13 patients, with electrodes implanted for epilepsy evaluation, who performed overt and imagined speech production tasks. Based on recent theories of speech neural processing, we extracted consistent and specific neural features usable for future brain computer interfaces, and assessed their performance to discriminate speech items in articulatory, phonetic, and vocalic representation spaces. While high-frequency activity provided the best signal for overt speech, both low- and higher-frequency power and local cross-frequency contributed to imagined speech decoding, in particular in phonetic and vocalic, i.e. perceptual, spaces. These findings show that low-frequency power and cross-frequency dynamics contain key information for imagined speech decoding.

Acoustic and Kinematic Correlates of Heterosyllabicity in Different Phonological Contexts

We investigate the temporal and kinematic properties of consonant gemination and heterosyllabic clusters as opposed to singletons and tautosyllabic clusters in Italian. The data show that the singleton versus geminate contrast is conveyed by specific kinematic properties in addition to systematic durational differences in both the consonantal and vocalic intervals; by contrast, tautosyllabic and heterosyllabic clusters differ significantly for the duration of the consonantal interval but do not vary systematically with respect to the vocalic interval and cannot be consistently differentiated at the kinematic level. We conclude that systematic variations in acoustic vowel duration and the kinematics of tongue tip gestures represent the phonetic correlates of the segmental phonological contrast between short and long consonants, rather than of syllable structure. Data are only partly consistent with the predictions of both moraic and gesture-based models of the syllable about the effects of syllable structure on speech production dynamics and call for a more gradient view of syllabification.

On the Benefits of Speech-Language Therapy for Individuals Born With Cleft Palate: A Systematic Review and Meta-Analysis of Individual Participant Data

Purpose: Cleft lip and/or palate (CLP) is a common birth defect, and after reconstructive surgery, about 50% of children at 5 years of age have speech deviations and are referred to speech-language therapy (SLT). The peer-reviewed evidence for the benefit of SLT has been uncertain. Our objective was to systematically review and meta-analytically summarize the benefit of SLT for individuals born with CLP. Method: A systematic search was conducted (last search on February 19, 2021) on studies evaluating SLT with pre and post measures on speech production, language ability, intelligibility, and/or patient-reported outcomes. We sought individual participant data (IPD) and evaluated on an individual level if the outcome measure had improved to a clinically relevant degree during SLT and if the outcome measure was on a level with peers or not after SLT. Meta-analyses and meta-regressions were applied to synthesize IPD across studies. Results: Thirty-four eligible studies were found. Nineteen studies provided IPD ( n = 343) for the main analysis on speech production. The synthesized information suggests that, during SLT, speech production improved to a clinically relevant degree for many individuals (95% CI [61%, 87%]) and that speech production was on a level with peers for some individuals after SLT (95% CI [10%, 34%]). Conclusions: The main strength of this meta-analysis is that we evaluated on an individual level pre- and post-intervention data based on considerations of clinical relevance. This approach allowed us to conclude that many individuals benefit from SLT and that further work on evaluating SLT in this patient group is meaningful. Supplemental Material https://doi.org/10.23641/asha.17700992

Discussions on Auditory-Perceptual Evaluation Performed in Patients With Voice Disorders

The auditory-perceptual evaluation of speech-language pathologists (SLP) in patients with voice disorders is often regarded as a touchstone in the multi-dimensional voice evaluation procedures and provides important information not available in other assessment modalities. Therefore, it is necessary for the SLPs to conduct a comprehensive and in-depth evaluation of not only voice but also the overall speech production mechanism, and they often encounter various difficulties in the evaluation process. In addition, SLPs should strive to avoid bias during the evaluation process and to maintain a wide and constant spectrum of severity for each parameter of voice quality. Lastly, it is very important for the SLPs to perform a team approach by documenting and delivering important information pertaining to auditory-perceptual characteristics in an appropriate and efficient way through close communication with the laryngologists.

Beyond Broca: Neural Architecture and Evolution of a Dual Motor Speech Coordination System

Classical neural architecture models of speech production propose a single system coordinating all the vocal articulators from lips to larynx. Here we propose a dual coordination system in which laryngeal control of pitch-related aspects of prosody and song are controlled by a dorsal premotor system while supralaryngeal articulation at the phonetic/syllabic level is controlled by a ventral premotor system. The separability of these neural systems supports models of the evolution of speech and language in which song-based communication was an early foundational stage.

Assessing Ecologically Valid Methods of Auditory Feedback Measurement in Individuals With Typical Speech

Purpose: Auditory feedback is thought to contribute to the online control of speech production. Yet, the standard method of estimating auditory feedback control (i.e., reflexive responses to auditory–motor perturbations), although sound, requires specialized instrumentation, meticulous calibration, unnatural tasks, and specific acoustic environments. The purpose of this study was to explore more ecologically valid features of speech production to determine their relationships with auditory feedback mechanisms. Method: Two previously proposed measures of within-utterance variability (centering and baseline variability) were compared with reflexive response magnitudes in 30 adults with typical speech. These three measures were estimated for both the laryngeal and articulatory subsystems of speech. Results: Regardless of the speech subsystem, neither centering nor baseline variability was shown to be related to reflexive response magnitudes. Likewise, no relationships were found between centering and baseline variability. Conclusions: Despite previous suggestions that centering and baseline variability may be related to auditory feedback mechanisms, this study did not support these assertions. However, the detection of such relationships may have required a larger degree of variability in responses, relative to that found in those with typical speech. Future research on these relationships is warranted in populations with more heterogeneous responses, such as children or clinical populations. Supplemental Material https://doi.org/10.23641/asha.17330546

Setting the Stage for Speech Production: Infants Prefer Listening to Speech Sounds With Infant Vocal Resonances

Purpose: Current models of speech development argue for an early link between speech production and perception in infants. Recent data show that young infants (at 4–6 months) preferentially attend to speech sounds (vowels) with infant vocal properties compared to those with adult vocal properties, suggesting the presence of special “memory banks” for one's own nascent speech-like productions. This study investigated whether the vocal resonances (formants) of the infant vocal tract are sufficient to elicit this preference and whether this perceptual bias changes with age and emerging vocal production skills. Method: We selectively manipulated the fundamental frequency ( f 0 ) of vowels synthesized with formants specifying either an infant or adult vocal tract, and then tested the effects of those manipulations on the listening preferences of infants who were slightly older than those previously tested (at 6–8 months). Results: Unlike findings with younger infants (at 4–6 months), slightly older infants in Experiment 1 displayed a robust preference for vowels with infant formants over adult formants when f 0 was matched. The strength of this preference was also positively correlated with age among infants between 4 and 8 months. In Experiment 2, this preference favoring infant over adult formants was maintained when f 0 values were modulated. Conclusions: Infants between 6 and 8 months of age displayed a robust and distinct preference for speech with resonances specifying a vocal tract that is similar in size and length to their own. This finding, together with data indicating that this preference is not present in younger infants and appears to increase with age, suggests that nascent knowledge of the motor schema of the vocal tract may play a role in shaping this perceptual bias, lending support to current models of speech development. Supplemental Material https://doi.org/10.23641/asha.17131805