Age-related changes in motor control during articulator visuomotor tracking

Systematic Review: Singing-Based Interventions to Improve Physical Functions Related to Aging Voice in Older Adults

PURPOSE

This systematic review aimed to evaluate the effects of singing as an intervention for aging voice.

METHOD

Quantitative studies of interventions for older adults with any medical condition that involves singing as training were reviewed, measured by respiration, phonation, and posture, which are the physical functions related to the aging voice. English and Chinese studies published until April 2024 were searched using 31 electronic databases, and seven studies were included. The included articles were assessed according to the Grading of Recommendations, Assessment, Development, and Evaluations rubric.

RESULTS

Seven studies were included. These studies reported outcome measures that were related to respiratory functions only. For the intervention effect, statistically significant improvements were observed in five of the included studies, among which three studies had large effect sizes. The overall level of evidence of the included studies was not high, with three studies having moderate levels and the rest having lower levels. The intervention activities included trainings other than singing. These non-singing training items may have caused co-intervention bias in the study results.

CONCLUSIONS

This systematic review suggests that singing as an intervention for older adults with respiratory and cognitive problems could improve respiration and respiratory-phonatory control. However, none of the included studies covers the other two of the physical functions related to aging voice (phonatory and postural functions). The overall level of evidence of the included studies was not high either. There is a need for more research evidence in singing-based intervention specifically for patient with aging voice.

Effects of Speaking Rate Changes on Speech Motor Variability in Adults

The relationship between speaking rate and speech motor variability was examined in three groups of neurotypical adults, n = 40; 15 young adults (18-30 years), 13 adults (31-40 years), and 12 middle-aged adults (41-50 years). Participants completed a connected speech task at three speaking rates (habitual, fast, and slow) where kinematic (lower lip movement) and acoustic data were obtained. Duration and variability were measured at each speaking rate. Findings revealed a complex relationship between speaking rate and variability. Adults from the middle age range (31-40 years) demonstrated shorter acoustic and kinematic durations compared with the oldest age group (41-50 years) during the habitual speaking rate condition. All adults demonstrated the greatest variability in the slow speaking rate condition, with no significant differences in variability between habitual and fast speaking rates. Interestingly, lip aperture variability was significantly lower in the youngest age group (18-30 years) compared with the two older groups during the fast speaking rate condition. Differences in measures of acoustic variability were not observed across the age levels. Strong negative correlations between kinematic/acoustic duration and lip aperture/acoustic variability in the youngest age group were revealed. Therefore, while a slow speaking rate does result in greater variability compared with habitual and fast speaking rates, longer durations of productions by the different age groups were not linked to higher spatiotemporal index (STI) values, suggesting that timing influences speech motor variability, but is not the sole contributor.

Oral dyspraxia in self-limited epilepsy with centrotemporal spikes: a comparative study with a control group

BACKGROUND

self-limited epilepsy with centrotemporal spikes, previously considered benign focal childhood epilepsy with centrotemporal spikes show clinical signs of involvement of Rolandic areas, mainly lower area, which may affect the planning and execution of motor sequences.

OBJECTIVE

This study aimed to evaluated oral praxis in children with self-limited epilepsy with centrotemporal spikes and compare to the age-matched control group.

METHODS

This was a descriptive study with 74 children with self-limited epilepsy with centrotemporal spikes, with the classical forms according to International League Against Epilepsy, and between 4 and 15 years of age, selected from the child neurology outpatient clinic of the Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil, and 239 age-matched and educational level-matched (convenience sampling) control children. All children were submitted to the battery of oral volitional movements, which consisted of 44 tests for oral movement (tongue, lip, cheek, jaw, and palate) and 34 phonemes and consonant cluster tasks, with simple and sequenced oral movements.

RESULTS

The mean age and standard deviation (SD) of children with epilepsy was 9.08 years (SD 2.55) and of controls 9.61 years (SD 3.12). The results showed significant differences between the groups with a poorer performance of children with epilepsy compared to children without epilepsy in simple and particularly in sequenced movements.

CONCLUSION

These findings can be attributed to the genetically determined immaturity of cortical structures related to motor planning in children with self-limited epilepsy with centrotemporal spikes.

Attention in post-lexical processes of utterance production: Dual-task cost in younger and older adults

There is a general agreement that speaking requires attention at least for conceptual and lexical processes of utterance production. However, conflicting results have been obtained with dual-task paradigms using either repetition tasks or more generally tasks involving limited loading of lexical selection. This study aimed to investigate whether post-lexical processes recruit attentional resources. We used a new dual-task paradigm in a set of experiments where a continuous verbal production task involved either high or low demand on lexical selection processes. Experiment 1 evaluates lexical and post-lexical processes with a semantic verbal fluency task, whereas Experiments 2 and 3 focus on post-lexical processes with a non-propositional speech task. In each experiment, two types of non-verbal secondary tasks were used: processing speed (simple manual reaction times) or inhibition (Go/No-go). In Experiment 1, a dual-task cost was observed on the semantic verbal fluency task and each non-verbal task. In Experiment 2, a dual-task cost appeared on the non-verbal tasks but not on the speech task. The same paradigm was used with older adults (Experiment 3), as increased effort in post-lexical processes has been associated with ageing. For older adults, a dual-task cost was also observed on the non-propositional verbal task when speech was produced with the inhibition non-verbal task. The results suggest an attentional cost on post-lexical processes and strategic effects in the resolution of the dual-task.

Ten Years of Research on Automatic Voice and Speech Analysis of People With Alzheimer's Disease and Mild Cognitive Impairment: A Systematic Review Article

Background: The field of voice and speech analysis has become increasingly popular over the last 10 years, and articles on its use in detecting neurodegenerative diseases have proliferated. Many studies have identified characteristic speech features that can be used to draw an accurate distinction between healthy aging among older people and those with mild cognitive impairment and Alzheimer's disease. Speech analysis has been singled out as a cost-effective and reliable method for detecting the presence of both conditions. In this research, a systematic review was conducted to determine these features and their diagnostic accuracy.

Methods: Peer-reviewed literature was located across multiple databases, involving studies that apply new procedures of automatic speech analysis to collect behavioral evidence of linguistic impairments along with their diagnostic accuracy on Alzheimer's disease and mild cognitive impairment. The risk of bias was assessed by using JBI and QUADAS-2 checklists.

Results: Thirty-five papers met the inclusion criteria; of these, 11 were descriptive studies that either identified voice features or explored their cognitive correlates, and the rest were diagnostic studies. Overall, the studies were of good quality and presented solid evidence of the usefulness of this technique. The distinctive acoustic and rhythmic features found are gathered. Most studies record a diagnostic accuracy over 88% for Alzheimer's and 80% for mild cognitive impairment.

Conclusion: Automatic speech analysis is a promising tool for diagnosing mild cognitive impairment and Alzheimer's disease. The reported features seem to be indicators of the cognitive changes in older people. The specific features and the cognitive changes involved could be the subject of further research.

Information Rate in Humans during Visuomotor Tracking

Previous investigations concluded that the human brain’s information processing rate remains fundamentally constant, irrespective of task demands. However, their conclusion rested in analyses of simple discrete-choice tasks. The present contribution recasts the question of human information rate within the context of visuomotor tasks, which provides a more ecologically relevant arena, albeit a more complex one. We argue that, while predictable aspects of inputs can be encoded virtually free of charge, real-time information transfer should be identified with the processing of surprises. We formalise this intuition by deriving from first principles a decomposition of the total information shared by inputs and outputs into a feedforward, predictive component and a feedback, error-correcting component. We find that the information measured by the feedback component, a proxy for the brain’s information processing rate, scales with the difficulty of the task at hand, in agreement with cost-benefit models of cognitive effort.

Preparation and Evaluation of Poly-γ-glutamic Acid Hydrogel Mixtures with Amlodipine Besylate: Effect on Ease of Swallowing and Taste Masking

The purpose of the study was to prepare a poly-γ-glutamic acid hydrogel (PGA gel), to evaluate physicochemical properties, its ease of swallowing using texture profile analysis (TPA) and its taste-masking effects on amlodipine besylate (AML) using the artificial taste sensor and human gustatory sensation testing. Using TPA, 0.5 and 1.0% (w/v) PGA gels in the absence of drug were within the range of acceptability for use in people with difficulty swallowing according to permission criteria published by the Japanese Consumers Affairs Agency. The elution of AML from prepared PGA gels was complete within an hour and the gel did not appear to influence the bioavailability of AML. The sensor output of the basic bitterness sensor AN0 in response to AML mixed with 0.5 and 1.0% PGA gels was suppressed to a significantly greater degree than AML mixed with 0.5 and 1.0% agar. In human gustatory sensation testing, 0.5 and 1.0% PGA gels containing AML showed a potent bitterness-suppressing effect. Finally, ¹H-NMR spectroscopic analysis was carried out to examine the mechanism of bitterness suppression when AML was mixed with PGA gel. The signals of the proton nearest to the nitrogen atom of AML shifted clearly upfield, suggesting an interaction between the amino group of AML and the carboxyl group of PGA gel. In conclusion, PGA gel is expected to be a useful excipient in formulations of AML, not only increasing ease of swallowing but also masking the bitterness of the basic drug.

Different Responses to Altered Auditory Feedback in Younger and Older Adults Reflect Differences in Lexical Bias

Purpose Previous work has found that both young and older adults exhibit a lexical bias in categorizing speech stimuli. In young adults, this has been argued to be an automatic influence of the lexicon on perceptual category boundaries. Older adults exhibit more top-down biases than younger adults, including an increased lexical bias. We investigated the nature of the increased lexical bias using a sensorimotor adaptation task designed to evaluate whether automatic processes drive this bias in older adults. Method A group of older adults ( n = 27) and younger adults ( n = 35) participated in an altered auditory feedback production task. Participants produced target words and nonwords under altered feedback that affected the 1st formant of the vowel. There were 2 feedback conditions that affected the lexical status of the target, such that target words were shifted to sound more like nonwords (e.g., less-liss) and target nonwords to sound more like words (e.g., kess-kiss). Results A mixed-effects linear regression was used to investigate the magnitude of compensation to altered auditory feedback between age groups and lexical conditions. Over the course of the experiment, older adults compensated (by shifting their production of 1st formant) more to altered auditory feedback when producing words that were shifted toward nonwords ( less-liss) than when producing nonwords that were shifted toward words ( kess-kiss). This is in contrast to younger adults who compensated more to nonwords that were shifted toward words compared to words that were shifted toward nonwords. Conclusion We found no evidence that the increased lexical bias previously observed in older adults is driven by a greater sensitivity to top-down lexical influence on perceptual category boundaries. We suggest the increased lexical bias in older adults is driven by postperceptual processes that arise as a result of age-related cognitive and sensory changes.

The basic reproductive ratio as a link between acquisition and change in phonotactics

Language acquisition and change are thought to be causally connected. We demonstrate a method for quantifying the strength of this connection in terms of the 'basic reproductive ratio' of linguistic constituents. It represents a standardized measure of reproductive success, which can be derived both from diachronic and from acquisition data. By analyzing phonotactic English data, we show that the results of both types of derivation correlate, so that phonotactic acquisition indeed predicts phonotactic change, and vice versa. After drawing that general conclusion, we discuss the role of utterance frequency and show that the latter exhibits destabilizing effects only on late acquired items, which belong to phonotactic periphery. We conclude that - at least in the evolution of English phonotactics - acquisition serves conservation, while innovation is more likely to occur in adult speech and affects items that are less entrenched but comparably frequent.

Tongue exercise and ageing effects on morphological and biochemical properties of the posterior digastric and temporalis muscles in a Fischer 344 Brown Norway rat model

OBJECTIVE

This study sought to examin effects of age and tongue exercise on the posterior digastric (opener) and the temporalis (closer). We hypothesized 1) age would result in differing morphological (cross sectional area) and biochemical (myosin heavy chain isoform) components of these muscles; 2) tongue exercise would result in coactivation of these muscles inducing a decrease in age-related differences between age groups.

DESIGN

Young adult (9 months) and old (32 months) Fischer 344 Brown Norway rats were randomized into a tongue exercise or control group. Post-training, posterior digastric and temporalis muscles were harvested and analyzed using: 1) Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) to assess percent myosin heavy chain (MyHC) content; 2) Immunohistochemical staining to determine cross sectional area (CSA).

RESULTS

A larger proportion of slowly contracting MyHC isoforms in the posterior digastric and temporalis muscles were found in old. No significant main effects for age or exercise in fiber size were found in posterior digastric muscle. An interaction between age and exercise for temporalis cross sectional area indicated the old exercise group had smaller average cross sectional area than all other groups. CONCLUSIONS FINDINGS: suggest that: 1) Increasing age induces biochemical changes in muscles of the jaw, specifically showing an increase the proportion of slower contracting MyHC isoforms; 2) Increasing age and tongue exercise induce a reduction in muscle fiber cross sectional area in the temporalis muscle only. However, continued study of these cranial muscle systems is warranted to better understand these changes that occur with age and exercise.

A review of swallow timing in the elderly

Many studies evaluate dysphagia in elderly patients and compare their swallowing to younger controls to assess the degree of swallowing impairment. Previous research suggests that changes should be expected in swallowing due to aging, and these changes need to be considered when performing swallowing assessments. A systematic review was conducted to elucidate the timing of swallowing in healthy. A comprehensive multiengine literature search was conducted to find articles studying swallowing in the healthy elderly, which yielded 22,852 articles of which 11 were judged to be relevant. Only articles using videofluoroscopy as an assessment method for swallowing timing were included. The articles underwent detailed review for study quality and data extraction. The eleven studies contained data for 32 different parameters, and 10 of the 11 studies compared elderly subjects to a younger group. Timing measures from the studies were compiled for analysis. In general, bolus transit times do not appear to change with age. Of note, elderly subjects tended to have a significantly delayed swallow response times and longer duration of upper esophageal sphincter opening. Results showed a large degree of variability across studies for each of the timing measures. Confidence intervals for timing in healthy older participants were computed across studies. Potential sources of variation were identified, including methodological, stimulus-related and participant-related sources. The results suggests that aging affects only a few very specific swallowing timing parameters, and many parameters appear to be unaffected by aging. Therefore, significant differences from a young reference sample should be interpreted as dysphagia rather than normal changes due to aging.

Effect of age on human-computer-interface control via neck electromyography

The purpose of this study was to determine the effect of age on visuomotor tracking using submental and anterior neck surface electromyography (sEMG) to assess feasibility of computer control via neck musculature, which allows people with little remaining motor function to interact with computers. Thirty-two healthy adults participated: sixteen younger adults aged 18 - 29 years and sixteen older adults aged 69 - 85 years. Participants modulated sEMG to achieve targets presented at different amplitudes using real-time visual feedback. Root-mean-squared (RMS) error was used to quantify tracking performance. RMS error was increased for older adults relative to younger adults. Older adults demonstrated more RMS error than younger adults as a function of increasing target amplitude. The differential effects of age found on static tracking performance in anterior neck musculature suggest more difficult translation of human-computer-interfaces controlled using anterior neck musculature for static tasks to older populations.

Bidirectional Interference Between Speech and Nonspeech Tasks in Younger, Middle-Aged, and Older Adults

PURPOSE

The purpose of this study was to examine divided attention over a large age range by looking at the effects of 3 nonspeech tasks on concurrent speech motor performance. The nonspeech tasks were designed to facilitate measurement of bidirectional interference, allowing examination of their sensitivity to speech activity. A cross-sectional design was selected to explore possible changes in divided-attention effects associated with age.

METHOD

Sixty healthy participants were separated into 3 groups of 20: younger (20s), middle-aged (40s), and older (60s) adults. Each participant completed a speech task (sentence repetitions) once in isolation and once concurrently with each of 3 nonspeech tasks: a semantic-decision linguistic task, a quantitative-comparison cognitive task, and a manual motor task. The nonspeech tasks were also performed in isolation.

RESULTS

Data from speech kinematics and nonspeech task performance indicated significant task-specific divided attention interference, with divided attention affecting speech and nonspeech measures in the linguistic and cognitive conditions and affecting speech measures in the manual motor condition. There was also a significant age effect for utterance duration.

CONCLUSIONS

The results increase what is known about bidirectional interference between speech and other concurrent tasks as well as age effects on speech motor control.

Motor practice effects and sensorimotor integration in adults who stutter: Evidence from visuomotor tracking performance

PURPOSE

The purpose of this study was to utilize a visuomotor tracking task, with both the jaw and hand, to add to the literature regarding non-speech motor practice and sensorimotor integration (outside of auditory-motor integration domain) in adults who do (PWS) and do not (PWNS) stutter.

METHOD

Participants were 15 PWS (14 males, mean age = 27.0) and 15 PWNS (14 males, mean age = 27.2). Participants tracked both predictable and unpredictable moving targets separately with their jaw and their dominant hand, and accuracy was assessed by calculating phase and amplitude difference between the participant and the target. Motor practice effect was examined by comparing group performance over consecutive tracking trials of predictable conditions as well as within the first trial of same conditions.

RESULTS

Results showed that compared to PWNS, PWS were not significantly different in matching either the phase (timing) or the amplitude of the target in both jaw and hand tracking of predictable and unpredictable targets. Further, there were no significant between-group differences in motor practice effects for either jaw or hand tracking. Both groups showed improved tracking accuracy within and between the trials.

CONCLUSION

Our findings revealed no statistically significant differences in non-speech motor practice effects and integration of sensorimotor feedback between PWS and PWNS, at least in the context of the visuomotor tracking tasks employed in the study. In general, both talker groups exhibited practice effects (i.e., increased accuracy over time) within and between tracking trials during both jaw and hand tracking. Implications for these results are discussed.

EDUCATIONAL OBJECTIVES

The reader will be able to: (a) describe the importance of motor learning and sensory-motor integration for speech, (b) summarize past research on PWS's performance during speech and nonspeech motor tasks, and (c) describe the relation between different aspects of speech and non-speech motor control and stuttering.

Visuomotor control of neck surface electromyography in Parkinson's disease

OBJECTIVE

To compare performance of individuals with Parkinson's disease (PD) and age-matched controls on a visuomotor tracking task controlled via surface electromyography (sEMG).

METHODS

Twenty-seven adults with PD and twenty-four older controls produced dry swallows and completed a visuomotor tracking task utilizing both static and dynamic targets. sEMG was recorded at the anterior neck and submental surface during both tasks.

RESULTS

There was no significant difference in visuomotor tracking ability between cohorts. Post hoc analyses indicated that there was no significant difference between participant groups in the strength or duration of swallows as measured by sEMG but that participants with PD showed a trend for decreased swallow durations at the anterior neck (padj = 0.067) whereas controls showed a trend for increased durations at the anterior neck (padj = 0.112), compared to the submental surface. However, there were no significant correlations between swallowing behavior and visuomotor tracking ability.

CONCLUSION

There were no significant differences in visuomotor tracking performance between individuals with PD and controls. Furthermore, there was no relationship between tracking ability and swallowing behavior. We conclude that sEMG-mediated biofeedback may have limited promise as a tool for treating PD-related dysphagia.

At the interface of sensory and motor dysfunctions and Alzheimer's disease

Recent evidence indicates that sensory and motor changes may precede the cognitive symptoms of Alzheimer's disease (AD) by several years and may signify increased risk of developing AD. Traditionally, sensory and motor dysfunctions in aging and AD have been studied separately. To ascertain the evidence supporting the relationship between age-related changes in sensory and motor systems and the development of AD and to facilitate communication between several disciplines, the National Institute on Aging held an exploratory workshop titled "Sensory and Motor Dysfunctions in Aging and AD." The scientific sessions of the workshop focused on age-related and neuropathologic changes in the olfactory, visual, auditory, and motor systems, followed by extensive discussion and hypothesis generation related to the possible links among sensory, cognitive, and motor domains in aging and AD. Based on the data presented and discussed at this workshop, it is clear that sensory and motor regions of the central nervous system are affected by AD pathology and that interventions targeting amelioration of sensory-motor deficits in AD may enhance patient function as AD progresses.

Effects of age and syntactic complexity on speech motor performance

PURPOSE

This study investigated the effect of age on articulatory movement and stability in young, middle-age, and older adults. It also examined the potential influence of linguistic complexity on speech motor control across utterances that differed in their length and grammatical complexity.

METHOD

There were 60 participants in 3 age groups: 20-30 years, 40-50 years, and 60-70 years, with equal numbers of men and women in each group. The speakers produced 10 repetitions of 5 different stimuli-each of which included the same bilabial-loaded phrase in different grammatical contexts-while their lip movements were recorded.

RESULTS

Participants from the 60-year-old group had significantly longer utterance durations, whereas those from the 20-year-old group had the highest jaw spatiotemporal index (STI) values. There were significant differences in the upper lip STI, displacement, and velocity as well as in vocal intensity for the longer, complex conditions compared with the shorter, phrase-only task. Overall, the differences in performance were minimal across grammatical complexity levels that were equal in length.

CONCLUSION

These findings suggest that speech motor control matures beyond young adulthood and that linguistic complexity in a repetitive task does not appear to have a consistent effect on measures of speech movement.

Presence of stop bursts and multiple bursts in individuals with Parkinson disease

Studies have reported that individuals with Parkinson Disease (PD) have imprecise articulation of stop consonants due to either slowness of articulators or decreased closure strength. The moment of release for stop consonants, called the burst, has been previously studied in individuals with PD and in other disorders. Multiple bursts (MBs) on the same stop consonant have been reported previously in some motor speech disorders, but no studies are known to have examined MBs in individuals with PD. The current study looked at the occurrences of bursts and MBs in initial stop consonants produced by nine individuals with PD (ON and OFF medication) and nine control speakers. Individuals with PD produced fewer overall bursts compared to control participants. In terms of place of articulation, individuals with PD primarily had loss of bursts in bilabial stops. In addition, individuals with PD had more MBs than control speakers, primarily in alveolars. Finally, no dopamine-related medication effects were found for occurrences of bursts or MBs in individuals with PD. Overall, the study provided evidence for loss of bursts and presence of MBs for stop consonants produced by individuals with PD.

Voice onset time and speakers' age: data from Hungarian

The aim of this paper was to investigate the VOT of voiceless plosives (/p, t, k/) in the speech of Hungarian-speaking elderly. Read speech of 25 old (70 to 90 years) and 25 young (21 to 32 years) was analyzed. In each recording, the VOT of phonologically short [p, t, k] was measured. Our data show that VOT values of all three types of voiceless plosives would exhibit significant differences both in old and in young Hungarians' speech. Bilabial and alveolar plosives had significantly longer VOT in old subjects' speech than in that of young subjects, while old subjects produced significantly shorter VOTs in pronouncing [k] than their younger peers. We argue that these results are attributable to (1) significantly slower rate of articulation (yielding longer speech sounds in general), and (2) the articulatory and aerodynamic background of the production of plosives.

Aging effects on sensorimotor integration: a comparison of effector systems and feedback modalities

Research on motor aging has focused on visuomotor effects in limb musculature, with few comparisons across effectors or feedback modalities. The authors examined steady fine force control in oral and manual effectors under visual and auditory feedback in 13 young (19-23 years old) and 13 older (60-77 years old) participants, hypothesizing that force variability would increase with aging (a) more in the finger than the lip and (b) for both feedback modalities. The magnitude of variability increased with age for both visuomotor and audiomotor tasks but age-related differences were greater in the lip than the finger. These results point to increased variability as a potential early marker of changing motor function (prior to loss of strength) that extends beyond the visuomotor system.

Auditory feedback control of vocal pitch during sustained vocalization: a cross-sectional study of adult aging

BACKGROUND

Auditory feedback has been demonstrated to play an important role in the control of voice fundamental frequency (F(0)), but the mechanisms underlying the processing of auditory feedback remain poorly understood. It has been well documented that young adults can use auditory feedback to stabilize their voice F(0) by making compensatory responses to perturbations they hear in their vocal pitch feedback. However, little is known about the effects of aging on the processing of audio-vocal feedback during vocalization.

METHODOLOGY/PRINCIPAL FINDINGS

In the present study, we recruited adults who were between 19 and 75 years of age and divided them into five age groups. Using a pitch-shift paradigm, the pitch of their vocal feedback was unexpectedly shifted ±50 or ±100 cents during sustained vocalization of the vowel sound/u/. Compensatory vocal F(0) response magnitudes and latencies to pitch feedback perturbations were examined. A significant effect of age was found such that response magnitudes increased with increasing age until maximal values were reached for adults 51-60 years of age and then decreased for adults 61-75 years of age. Adults 51-60 years of age were also more sensitive to the direction and magnitude of the pitch feedback perturbations compared to younger adults.

CONCLUSION

These findings demonstrate that the pitch-shift reflex systematically changes across the adult lifespan. Understanding aging-related changes to the role of auditory feedback is critically important for our theoretical understanding of speech production and the clinical applications of that knowledge.

Neural control of the lips differs for young and older adults following a perturbation

Aging impairs the control of many skilled movements including speech. The purpose of this paper was to investigate whether young and older adults adapt to lower lip perturbations during speech differently. Twenty men (10 young, 26 ± 3 years of age; 10 older, 60 ± 9 years of age) were requested to repeat the word ("papa") 300 times. In 15% of the trials, the subjects experienced a mechanical perturbation on the lower lip. Displacement and neural activation (EMG) of the upper and lower lips were evaluated. Perturbations to the lower lip caused a greater increase in the maximum displacement of the lower lip for older adults compared with young adults (34.7 ± 19% vs. 13.4 ± 17%; P=0.017). Furthermore, young adults exhibited significantly greater 30-100 Hz normalized EMG power for the lower lip compared to the upper lip (P<0.005). In young adults, changes from normal to perturbed trials in the 30-50 Hz frequency band of the EMG were negatively correlated to the changes from normal to perturbed trials in the lower lip maximum displacement (R (2) =0.48; P=0.025). It is concluded that young adults adapt better to lower lip perturbations compared with older adults and that the associated neural activation strategy of the involved muscle is different for the two age groups.

Auditory feedback control of voice fundamental frequency in school children

The present study was intended to address how the online control of voice fundamental frequency (F(0)) during vocalization develops from school children to young adults. Nineteen school children (7-12 years old) and twenty-one young adults (19-27 years old) participated in this experiment. They were asked to sustain a vowel sound /u/ while their voice pitch feedback was randomly shifted (+/-50, +/-100, +/-200, and +/-500 cents) and fed back to them instantaneously over headphones. Results showed that school children produced significantly larger but slower compensatory responses to voice pitch feedback perturbations than young adults. Response latencies became longer with the increase in pitch perturbation magnitude, but no systematic changes were found as a function of stimulus direction. In addition, the number of responses "following" the stimulus direction across different stimulus magnitudes for school children was greater than for young adults. These findings demonstrate developmental changes of vocal responses to pitch feedback perturbations during vocalization from school children to young adults, and suggest that vocal responses can serve as an objective index of the maturation of the audio-vocal system.

Between-speaker and within-speaker variation in speech tempo of American English

This study characterizes the speech tempo (articulation rate, excluding pauses) of two distinct varieties of American English taking into account both between-speaker and within-speaker variation. Each of 192 speakers from Wisconsin (the northern variety) and from North Carolina (the southern variety), men and women, ranging in age from children to old adults, read a set of sentences and produced a spontaneous unconstrained talk. Articulation rate in spontaneous speech was modeled using fixed-mixed effects analyses. The models explored the effects of the between-speaker factors dialect, age and gender and included each phrase and its length as a source of both between- and within-speaker variation. The major findings are: (1) Wisconsin speakers speak significantly faster and produce shorter phrases than North Carolina speakers; (2) speech tempo changes across the lifespan, being fastest for individuals in their 40s; (3) men speak faster than women and this effect is not related to the length of phrases they produce. Articulation rate in reading was slower than in speaking and the effects of gender and age also differed in reading and spontaneous speech. The effects of dialect in reading remained the same, showing again that Wisconsin speakers had faster articulation rates than did North Carolina speakers.

Age-related changes in the functional neuroanatomy of overt speech production

Alterations of existing neural networks during healthy aging, resulting in behavioral deficits and changes in brain activity, have been described for cognitive, motor, and sensory functions. To investigate age-related changes in the neural circuitry underlying overt non-lexical speech production, functional MRI was performed in 14 healthy younger (21-32 years) and 14 healthy older individuals (62-84 years). The experimental task involved the acoustically cued overt production of the vowel /a/ and the polysyllabic utterance /pataka/. In younger and older individuals, overt speech production was associated with the activation of a widespread articulo-phonological network, including the primary motor cortex, the supplementary motor area, the cingulate motor areas, and the posterior superior temporal cortex, similar in the /a/ and /pataka/ condition. An analysis of variance with the factors age and condition revealed a significant main effect of age. Irrespective of the experimental condition, significantly greater activation was found in the bilateral posterior superior temporal cortex, the posterior temporal plane, and the transverse temporal gyri in younger compared to older individuals. Significantly greater activation was found in the bilateral middle temporal gyri, medial frontal gyri, middle frontal gyri, and inferior frontal gyri in older vs. younger individuals. The analysis of variance did not reveal a significant main effect of condition and no significant interaction of age and condition. These results suggest a complex reorganization of neural networks dedicated to the production of speech during healthy aging.

Age-related changes in acoustic characteristics of adult speech

This paper addresses effects of age and sex on certain acoustic properties of speech, given conflicting findings on such effects reported in prior research. The speech of 27 younger adults (15 women, 12 men; mean age 25.5 years) and 59 older adults (32 women, 27 men; mean age 75.2 years) was evaluated for identification of differences for sex and age group across measures of fundamental and formant frequencies (F0, F1, F2 and F3) and voice onset time (VOT). There were significant sex-by-age group interactions for F0, F1, and VOT, some of which were specific to individual speech sounds. The findings suggest that further research on aging speech should focus on sex differences and the potential influence such changes may have on communication abilities of older adults with hearing loss.

LEARNING OUTCOMES

The reader will be able to understand and describe (1) possible changes in specific acoustic properties with age, (2) how these changes may differ for women and men, and (3) the potential impact these changes may have on the speech understanding of older individuals with hearing loss.

Relationship between age, percentage of consonants correct and speech rate

BACKGROUND

There is a lack of information regarding the relationship between age, speech rate and speech performance.

AIM

To analyze and to compare the performance of children according to age, Percentage of Consonants Correct (PCC) and speech rate, and to determine the relationship between these variables.

METHOD

Participants of this study were two hundred children divided in three different age groups: 6:0 to 8:0 years (Group I), 8:1 to 10:0 years (Group II), and 10:1 to 12:6 years (Group III). The following tests were used: speech rate tasks, imitation and picture naming (ABFW-Language test for children) and the Percentage of Consonants Correct (PCC) was calculated. Statistical analysis was performed using ANOVA for inter-group analysis, followed by the Tukey Test. The coefficient of Pearson Correlation was used to analyze the relationship between age, speech rate and speech performance (PCC).

RESULTS

There was a significant difference between the PCC and speech rate when comparing the three groups (p<0.001). Regarding speech rate test, using /pataka/ as a stimulus, there were significant differences between Group I and the two other groups (p<0.01). There was a significant and positive correlation between age, the PCC and speech rate (p<0.05).

CONCLUSION

Speech performance, measured by the PCC, and speech rate increased according to age, resulting in significant differences between the three age groups. The increase of the PCC indexes and of speech rate were directly proportional.

Visuomotor tracking abilities of speakers with apraxia of speech or conduction aphasia

This investigation examined the visuomotor tracking abilities of persons with apraxia of speech (AOS) or conduction aphasia (CA). In addition, tracking performance was correlated with perceptual judgments of speech accuracy. Five individuals with AOS and four with CA served as participants, as well as an equal number of healthy controls matched by age and gender. Participants tracked predictable (sinusoidal) and unpredictable signals using jaw and lip movements transduced with strain gauges. Tracking performance in participants with AOS was poorest for predictable signals, with decreased kinematic measures of cross-correlation and gain ratio and increased target-tracker difference. In contrast, tracking of the unpredictable signal by participants with AOS was performed as well as for other groups (e.g. participants with CA, healthy controls). Performance of the subjects with AOS on the predictable tracking task was found to strongly correlate with perceptual judgments of speech. These findings suggest that motor control capabilities are impaired in AOS, but not in CA. Results suggest that AOS has its basis in motor programming deficits, not impaired motor execution.

Influence of continual biofeedback on jaw pursuit-tracking in healthy adults and in adults with apraxia plus aphasia

Apraxia of speech (AOS) is a disorder of motor programming resulting from damage to premotor or anterior insula cortex. The authors used a pursuit visuomotor tracking task to test whether such a disorder interferes with development of motor programs or with modification of existing programs via integration of feedback. Healthy older adults (n = 15) and adults with AOS plus aphasia and nonverbal apraxia (n = 8) performed a jaw movement task with (a) continuous visual feedback of a target movement pattern and their jaw movement and (b) no feedback. Healthy speakers were more accurate and less variable with feedback, suggesting accurate development of a program and feedback integration. Apraxic individuals' performance accuracy and response to feedback suggested that the neurological damage impairs both development of new programs and efficient integration of feedback.

Speech motor control in fluent and dysfluent speech production of an individual with apraxia of speech and Broca's aphasia

Apraxia of speech (AOS) is typically described as a motor-speech disorder with clinically well-defined symptoms, but without a clear understanding of the underlying problems in motor control. A number of studies have compared the speech of subjects with AOS to the fluent speech of controls, but only a few have included speech movement data and if so, this was primarily restricted to the study of single articulators. If AOS reflects a basic neuromotor dysfunction, this should somehow be evident in the production of both dysfluent and perceptually fluent speech. The current study compared motor control strategies for the production of perceptually fluent speech between a young woman with apraxia of speech (AOS) and Broca's aphasia and a group of age-matched control speakers using concepts and tools from articulation-based theories. In addition, to examine the potential role of specific movement variables on gestural coordination, a second part of this study involved a comparison of fluent and dysfluent speech samples from the speaker with AOS. Movement data from the lips, jaw and tongue were acquired using the AG-100 EMMA system during the reiterated production of multisyllabic nonwords. The findings indicated that although in general kinematic parameters of fluent speech were similar in the subject with AOS and Broca's aphasia to those of the age-matched controls, speech task-related differences were observed in upper lip movements and lip coordination. The comparison between fluent and dysfluent speech characteristics suggested that fluent speech was achieved through the use of specific motor control strategies, highlighting the potential association between the stability of coordinative patterns and movement range, as described in Coordination Dynamics theory.

Philosophy of research in motor speech disorders

The primary objective of this position paper is to assess the theoretical and empirical support that exists for the Mayo Clinic view of motor speech disorders in general, and for oromotor, nonverbal tasks as a window to speech production processes in particular. Literature both in support of and against the Mayo clinic view and the associated use of oromotor, nonverbal tasks, is reviewed, along with literature from normal speech production and neurophysiology. This literature is organized and analysed to show that theoretical and experimental support for the Mayo view is weak at best, and that the frequent appeal to oromotor, nonverbal tasks is misguided. We conclude that studies of speech production in motor speech disorders, rather than oromotor nonverbal control or of neurological signs, is the correct approach for advancing the field.

Bolus location at the initiation of the pharyngeal stage of swallowing in healthy older adults

This study characterized the vertical position of the bolus head at the onset of the pharyngeal swallow in healthy older adults. Lateral-view videofluoroscopic (VF) images were obtained from ten healthy volunteers (age-71.6 +/- 7.5 years, mean+/- SD) as they swallowed 5-cc thin liquid barium aliquots. For each swallow, the bolus head and several anatomic landmarks were digitally recorded from the image in which pharyngeal swallow-related hyoid bone elevation began. Vertical distance between the bolus head and the intersection of the tongue base and mandibular ramus (TMI) was computed. Bolus head position at swallow onset ranged from 47.4-mm above to 34.9-mm below the TMI (2.2 +/- 14.4-mm, mean +/- SD). Although the bolus head was below the level of the TMI for the majority of swallows, neither penetration nor aspiration occurred. For individual subjects, mean bolus head position ranged from 25.8 +/- 5.0-mm above to 15.5 +/- 6.5-mm below the TMI. Whereas five of ten subjects initiated the pharyngeal swallow with the bolus head consistently above or consistently below the TMI, five subjects initiated swallowing with the bolus head either above or below the TMI across trials. Older adults commonly initiate thin-liquid swallows with the bolus head well below the TMI without associated penetration or aspiration. Thus, bolus position alone does not differentiate between normal and pathologic swallowing within the healthy elderly. Bolus position at pharyngeal swallow onset can vary substantially from trial to trial within an individual, suggesting that the triggering of swallowing depends on multiple influences.

Motor control in children and adults during a non-speech oral task

Although decreased accuracy and increased variability of movement is a common developmental finding, the nature of these performance patterns remains poorly understood. The present study examined the accuracy and stability of several aspects of oral motor control. Specifically, we examined the control of absolute timing (temporal parameterization), absolute amplitude (amplitude parameterization), and relative timing and amplitude (generalized motor programs) in children and adults during a lip plus jaw opening and closing task. As was the case with similar reports, we found that children were both less accurate and less stable in their assignment of temporal and amplitude parameters. However, we further found that although children's underlying movement patterns were less accurate than those of adults, children exhibited similar variability in their generalized motor programs. The results are discussed within the framework of a schema model of motor control (Schmidt, 1975) with reference to the strategic allocation of resources during motor learning (e.g., Clark & Robin, 1998).