Does pre-speech auditory modulation reflect processes related to feedback monitoring or speech movement planning?

Previous studies have revealed that auditory processing is modulated during the planning phase immediately prior to speech onset. To date, the functional relevance of this pre-speech auditory modulation (PSAM) remains unknown. Here, we investigated whether PSAM reflects neuronal processes that are associated with preparing auditory cortex for optimized feedback monitoring as reflected in online speech corrections.

Does pre-speech auditory modulation reflect processes related to feedback monitoring or speech movement planning?

Previous studies have revealed that auditory processing is modulated during the planning phase immediately prior to speech onset. To date, the functional relevance of this pre-speech auditory modulation (PSAM) remains unknown. Here, we investigated whether PSAM reflects neuronal processes that are associated with preparing auditory cortex for optimized feedback monitoring as reflected in online speech corrections.

Electroencephalographic Classification Reveals Atypical Speech Motor Planning in Stuttering Adults.

Purpose: This study explores speech motor planning in adults who stutter (AWS) and adults who do not stutter (ANS) by applying machine learning algorithms to electroencephalographic (EEG) signals. In this study, we developed a technique to holistically examine neural activity differences in speaking and silent reading conditions across the entire cortical surface. This approach allows us to test the hypothesis that AWS will exhibit lower separability of the speech motor planning condition.

Lateralization and Time-Course of Cortical Phonological Representations during Syllable Production.

Spoken language contains information at a broad range of timescales, from phonetic distinctions on the order of milliseconds to semantic contexts which shift over seconds to minutes. It is not well understood how the brain's speech production systems combine features at these timescales into a coherent vocal output. We investigated the spatial and temporal representations in cerebral cortex of three phonological units with different durations: consonants, vowels, and syllables.

Placebo effects of transcranial direct current stimulation on motor skill acquisition.

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique used in neurorehabilitation to enhance motor training. However, its benefits to motor training can be difficult to reproduce across research studies. It is possible that the observed benefits of tDCS are not directly related to the intervention itself but rather to the brain-mind responses elicited by the treatment context, commonly known as a placebo effect.

Effects of Gradual and Sudden Introduction of Perturbations on Adaptive Responses to Formant-Shift and Formant-Clamp Perturbations.

Purpose: When the speech motor system encounters errors, it generates adaptive responses to compensate for the errors. Unlike errors induced by formant-shift perturbations, errors induced by formant-clamp perturbations do not correspond with the speaker's speech (i.e.

The Impact of Bimodal Hearing on Speech Acoustics of Vowel Production in Adult Cochlear Implant Users.

Purpose: This study aimed to investigate the acoustic changes in vowel production with different forms of auditory feedback via cochlear implant (CI), hearing aid (HA), and bimodal hearing (CI + HA).

Method: Ten post-lingually deaf adult bimodal CI users (aged 50-78 years) produced English vowels /i/, /ɛ/, /æ/, /ɑ/, /ʊ/, and /u/ in the context of /hVd/ during short-term use of no device (ND), HA, CI, and CI + HA. Segmental features (first formant frequency [ ], second formant frequency [ ], and vowel space area) and suprasegmental features (duration, intensity, and fundamental frequency [ ]) of vowel production were analyzed.

Quantitatively characterizing reflexive responses to pitch perturbations.

Background: Reflexive pitch perturbation experiments are commonly used to investigate the neural mechanisms underlying vocal motor control. In these experiments, the fundamental frequency-the acoustic correlate of pitch-of a speech signal is shifted unexpectedly and played back to the speaker via headphones in near real-time. In response to the shift, speakers increase or decrease their fundamental frequency in the direction opposing the shift so that their perceived pitch is closer to what they intended.

Impact of Startling Acoustic Stimuli on Word Repetition in Individuals With Aphasia and Apraxia of Speech Following Stroke.

Purpose: The StartReact effect, whereby movements are elicited by loud, startling acoustic stimuli (SAS), allows the evaluation of movements when initiated through involuntary circuitry, before auditory feedback. When StartReact is applied during poststroke upper extremity movements, individuals exhibit increased muscle recruitment, reaction times, and reaching distances. StartReact releases unimpaired speech with similar increases in muscle recruitment and reaction time.

Feedback and Feedforward Auditory-Motor Processes for Voice and Articulation in Parkinson's Disease.

Purpose: Unexpected and sustained manipulations of auditory feedback during speech production result in "reflexive" and "adaptive" responses, which can shed light on feedback and feedforward auditory-motor control processes, respectively. Persons with Parkinson's disease (PwPD) have shown aberrant reflexive and adaptive responses, but responses appear to differ for control of vocal and articulatory features. However, these responses have not been examined for both voice and articulation in the same speakers and with respect to auditory acuity and functional speech outcomes (speech intelligibility and naturalness).

A Computational Model for Estimating the Speech Motor System's Sensitivity to Auditory Prediction Errors.

Purpose The speech motor system uses feedforward and feedback control mechanisms that are both reliant on prediction errors. Here, we developed a state-space model to estimate the error sensitivity of the control systems. We examined (a) whether the model accounts for the error sensitivity of the control systems and (b) whether the two systems have similar error sensitivity.

Dissociated Development of Speech and Limb Sensorimotor Learning in Stuttering: Speech Auditory-motor Learning is Impaired in Both Children and Adults Who Stutter.

Stuttering is a neurodevelopmental disorder of speech fluency. Various experimental paradigms have demonstrated that affected individuals show limitations in sensorimotor control and learning. However, controversy exists regarding two core aspects of this perspective.

The Relation of Articulatory and Vocal Auditory-Motor Control in Typical Speakers.

Purpose The purpose of this study was to explore the relationship between feedback and feedforward control of articulation and voice by measuring reflexive and adaptive responses to first formant ( ) and fundamental frequency ( ) perturbations. In addition, perception of and perturbation was estimated using passive (listening) and active (speaking) just noticeable difference paradigms to assess the relation of auditory acuity to reflexive and adaptive responses. Method Twenty healthy women produced single words and sustained vowels while the or of their auditory feedback was suddenly and unpredictably perturbed to assess reflexive responses or gradually and predictably perturbed to assess adaptive responses.

Compensatory Responses to Formant Perturbations Proportionally Decrease as Perturbations Increase.

Purpose We continuously monitor our speech output to detect potential errors in our productions. When we encounter errors, we rapidly change our speech output to compensate for the errors. However, it remains unclear whether we adjust the magnitude of our compensatory responses based on the characteristics of errors.

Noninvasive neurostimulation of left ventral motor cortex enhances sensorimotor adaptation in speech production.

Sensorimotor adaptation-enduring changes to motor commands due to sensory feedback-allows speakers to match their articulations to intended speech acoustics. How the brain integrates auditory feedback to modify speech motor commands and what limits the degree of these modifications remain unknown. Here, we investigated the role of speech motor cortex in modifying stored speech motor plans.

The Orofacial Somatosensory System Is Modulated During Speech Planning and Production.

Purpose In our previous studies, we showed that the brain modulates the auditory system, and the modulation starts during speech planning. However, it remained unknown whether the brain uses similar mechanisms to modulate the orofacial somatosensory system. Here, we developed a novel behavioral paradigm to (a) examine whether the somatosensory system is modulated during speech planning and (b) determine the somatosensory modulation's time course during planning and production.

Auditory Feedback Control Mechanisms Do Not Contribute to Cortical Hyperactivity Within the Voice Production Network in Adductor Spasmodic Dysphonia.

Purpose Adductor spasmodic dysphonia (ADSD), the most common form of spasmodic dysphonia, is a debilitating voice disorder characterized by hyperactivity and muscle spasms in the vocal folds during speech. Prior neuroimaging studies have noted excessive brain activity during speech in participants with ADSD compared to controls. Speech involves an auditory feedback control mechanism that generates motor commands aimed at eliminating disparities between desired and actual auditory signals.

A Simple 3-Parameter Model for Examining Adaptation in Speech and Voice Production.

Sensorimotor adaptation experiments are commonly used to examine motor learning behavior and to uncover information about the underlying control mechanisms of many motor behaviors, including speech production. In the speech and voice domains, aspects of the acoustic signal are shifted/perturbed over time via auditory feedback manipulations. In response, speakers alter their production in the opposite direction of the shift so that their perceived production is closer to what they intended.

Limited Pre-Speech Auditory Modulation in Individuals Who Stutter: Data and Hypotheses.

Purpose We review and interpret our recent series of studies investigating motor-to-auditory influences during speech movement planning in fluent speakers and speakers who stutter. In those studies, we recorded auditory evoked potentials in response to probe tones presented immediately prior to speaking or at the equivalent time in no-speaking control conditions. As a measure of pre-speech auditory modulation (PSAM), we calculated changes in auditory evoked potential amplitude in the speaking conditions relative to the no-speaking conditions.

Auditory gating in adults with dyslexia: An ERP account of diminished rapid neural adaptation.

Objective: A recent functional magnetic resonance imaging (fMRI) study of adults with dyslexia showed a general deficit in suppressing responses to various types of repetitive stimuli. This diminished neural adaptation may interfere with implicit learning and forming stable word representations. With fMRI, spatial but not temporal characteristics of the adaptation response could be identified.

Successful auditory motor adaptation requires task-relevant auditory errors.

When we produce speech movements, we also predict the auditory consequences of the movements. We use discrepancies between our predictions and incoming auditory information to modify our future movements (adapt). Although auditory errors are crucial for speech motor learning, not all perceived auditory errors are consequences of our own actions.

Production Variability and Categorical Perception of Vowels Are Strongly Linked.

Theoretical models of speech production suggest that the speech motor system (SMS) uses auditory goals to determine errors in its auditory output during vowel production. This type of error calculation indicates that within-speaker production variability of a given vowel is related to the size of the vowel's auditory goal. However, emerging evidence suggests that the SMS may also take into account perceptual knowledge of vowel categories (in addition to auditory goals) to estimate errors in auditory feedback.

An Investigation of Compensation and Adaptation to Auditory Perturbations in Individuals With Acquired Apraxia of Speech.

Two auditory perturbation experiments were used to investigate the integrity of neural circuits responsible for speech sensorimotor adaptation in acquired apraxia of speech (AOS). This has implications for understanding the nature of AOS as well as normal speech motor control. Two experiments were conducted.

Investigation of Feedback Schedules on Speech Motor Learning in Older Adults.

Background: The principles of motor learning (PML) emerged from studies of limb motor skills in healthy, young adults. The applicability of these principles to speech motor learning, and to older adults, is uncertain.

Aims: The purpose of this study was to examine one PML, feedback frequency, and its effect on retention and generalization of a novel speech and comparable tracing task.

Vocal Biomarkers of Mild-to-Moderate Hearing Loss in Children and Adults: Voiceless Sibilants.

Purpose: The purpose of this study was to determine if an objective measure of speech production could serve as a vocal biomarker for the effects of high-frequency hearing loss on speech perception. It was hypothesized that production of voiceless sibilants is governed sufficiently by auditory feedback that high-frequency hearing loss results in subtle but significant shifts in the spectral characteristics of these sibilants.

Method: Sibilant production was examined in individuals with mild to moderately severe congenital (22 children; 8-17 years old) and acquired (23 adults; 55-80 years old) hearing losses.