Tracking the Costs of Clear and Loud Speech: Interactions Between Speech Motor Control and Concurrent Visuomotor Tracking

Speech Kinematics and Perioral Muscle Activity Are Influenced by Stroop Effects

PURPOSE

The current project aimed to examine the effects of two experimental cognitive-linguistic paradigms, the Stroop task and a primed Stroop task, on speech kinematics and perioral muscle activation.

METHOD

Acoustic, kinematic, and surface electromyographic data were collected from the verbal responses of 30 young adult healthy control participants in choice response, classic Stroop, and primed Stroop tasks. The classic and primed Stroop tasks included congruent and incongruent trials. Across all three tasks, the set of possible responses was limited to the same three possible color words (red, green, and black) to facilitate performance comparisons between tasks.

RESULTS

Trials with ink-word incongruence in the Stroop tasks resulted in significantly higher muscle activation in the upper lip during response selection. In addition, a prime word within the Stroop task resulted in more spatial variation in lip + jaw movements for the spoken responses. These results were accompanied by the expected longer response times for incongruent trials in both classic and primed Stroop tasks.

CONCLUSIONS

These findings may suggest that more central cognitive-linguistic interference processes may lead to inefficiencies in more peripheral speech motor control. Future research should investigate the pattern of these effects in older adults with and without motor speech disorders for research and clinical applications.

Effect of clear speech on acoustic measures of dysprosody in Parkinson disease for different reading tasks

PURPOSE

The purpose of the study was to determine the effect of clear speech instruction on acoustic measures of dysprosody between reading passages of differing linguistic content for speakers with and without Parkinson Disease (PD).

METHOD

Ten speakers with PD and 10 controls served as participants and read five simple and three standard reading stimuli twice. First, speakers read habitually and then following clear speech instruction. Acoustic measures of fundamental frequency variation (semitone standard deviation, STSD), articulation rate, and between-complex pause durations were calculated.

RESULT

Results indicated speakers with PD exhibited less fundamental frequency variation than controls across reading stimuli and instructions. All speakers exhibited lower STSD and longer between-complex pause durations for the standard compared to simple reading stimuli. For clear speech, all speakers reduced articulation rate and increased between-complex pause durations in both simple and standard reading stimuli. However, speakers with PD exhibited a significantly less robust reduction in articulation rate for clear speech than control speakers for all reading stimuli.

CONCLUSION

Linguistic content of reading stimuli contributes to differences in fundamental frequency variation and pause duration for all speakers. All speakers reduced articulation rate for clear speech compared to habitual instruction, but speakers with PD did so to a lesser extent than controls. Linguistic content of reading stimuli to examine dysprosody in PD should be considered for clinical application.

Feedback From Automatic Speech Recognition to Elicit Clear Speech in Healthy Speakers

PURPOSE

This study assessed the effectiveness of feedback generated by automatic speech recognition (ASR) for eliciting clear speech from young, healthy individuals. As a preliminary step toward exploring a novel method for eliciting clear speech in patients with dysarthria, we investigated the effects of ASR feedback in healthy controls. If successful, ASR feedback has the potential to facilitate independent, at-home clear speech practice.

METHOD

Twenty-three healthy control speakers (ages 23-40 years) read sentences aloud in three speaking modes: Habitual, Clear (over-enunciated), and in response to ASR feedback (ASR). In the ASR condition, we used Mozilla DeepSpeech to transcribe speech samples and provide participants with a value indicating the accuracy of the ASR's transcription. For speakers who achieved sufficiently high ASR accuracy, noise was added to their speech at a participant-specific signal-to-noise ratio to ensure that each participant had to over-enunciate to achieve high ASR accuracy.

RESULTS

Compared to habitual speech, speech produced in the ASR and Clear conditions was clearer, as rated by speech-language pathologists, and more intelligible, per speech-language pathologist transcriptions. Speech in the Clear and ASR conditions aligned on several acoustic measures, particularly those associated with increased vowel distinctiveness and decreased speaking rate. However, ASR accuracy, intelligibility, and clarity were each correlated with different speech features, which may have implications for how people change their speech for ASR feedback.

CONCLUSIONS

ASR successfully elicited outcomes similar to clear speech in healthy speakers. Future work should investigate its efficacy in eliciting clear speech in people with dysarthria.

Order Affects Clear and Loud Speech Response

PURPOSE

The purpose of this investigation was to examine the impact of instruction order on the speech production response when adopting higher effort speaking styles, specifically loud and clear speech.

METHOD

Speech intensity, lip aperture range, and speech rate data were collected from 24 talkers who repeated the utterance "Buy Bobby a puppy" using habitual, clear, and loud speech. Participants were assigned in quasi-random fashion to one of two groups: a Clear-Loud Group (11 participants; order: habitual-clear-loud) or a Loud-Clear Group (13 participants; order: habitual-loud-clear).

RESULTS

Talkers in the Clear-Loud Group exhibited higher speech intensity during the loud style compared with those who performed the Loud-Clear Group. Furthermore, talkers in the Clear-Loud Group retained the increases lip aperture range and reductions in speech rate associated with the clear style when producing the loud style. Conversely, talkers in the Loud-Clear Group exhibited significant increases in lip aperture range between the habitual and loud styles and between the loud and clear styles. Additionally, the Loud-Clear Group exhibited a reduction in speech rate only during the clear style, as no differences in speech rate were observed between the habitual and loud styles.

CONCLUSIONS

These findings may suggest that producing a higher effort style leads to carry-over effects in subsequent styles. Future research should investigate factors that moderate the degree of order effects for both research and clinical purposes. For instance, if generalizable, the compounding carry-over effects may prove advantageous for certain clinical populations.

Quantifying Spatial and Temporal Variability of Clear and Loud Speech Produced While Performing a Concurrent Visuomotor Task

PURPOSE

The purpose of this research note was to quantify the impact of concurrent performance of an attention-demanding secondary task on utterance-to-utterance movement variability associated with higher effort speaking styles, namely, clear and loud speech.

METHOD

Lip and jaw kinematics collected as part of a prior study were analyzed. Participants repeated "Buy Bobby a puppy" using habitual, loud, and clear speech styles in isolation and while performing a secondary tracking task. The lip aperture (LA) signal was segmented based on opening and closing gestures associated with the utterance. The standard deviation of each segment duration was calculated to quantify temporal variability. To quantify spatial variability, each segment was first time normalized. The mean standard deviation of the overlapping time-normalized LA amplitudes was computed for each segment from the repetitions produced in each speech style and condition (speaking in isolation vs. speaking while tracking). A relative measure of spatial variation was also computed to account for the potential impact of articulatory scaling.

RESULTS

Clear speech was associated with greater temporal and spatial variability than the habitual and loud styles. In the habitual style, talkers also exhibited a slight reduction in absolute spatial variability when speaking while tracking compared to speaking in isolation. The reduction in absolute spatial variability was likely associated with the concomitant reduction in LA range of motion, as there was no change in the relative spatial variability between conditions.

CONCLUSION

The current investigation expands prior work by quantifying spatial and temporal characteristics of different speaking styles performed in isolation and while concurrently performing an attention-demanding visuomotor task.

Clear Speech Variants: An Investigation of Intelligibility and Speaker Effort in Speakers With Parkinson's Disease

PURPOSE

This study investigated the effects of three clear speech variants on sentence intelligibility and speaking effort for speakers with Parkinson's disease (PD) and age- and sex-matched neurologically healthy controls.

METHOD

Fourteen speakers with PD and 14 neurologically healthy speakers participated. Each speaker was recorded reading 18 sentences from the Speech Intelligibility Test in their habitual speaking style and for three clear speech variants: clear (SC; given instructions to speak clearly), hearing impaired (HI; given instructions to speak with someone with a hearing impairment), and overenunciate (OE; given instructions to overenunciate each word). Speakers rated the amount of physical and mental effort exerted during each speaking condition using visual analog scales (averaged to yield a metric of overall speaking effort). Sentence productions were orthographically transcribed by 50 naive listeners. Linear mixed-effects models were used to compare intelligibility and speaking effort across the clear speech variants.

RESULTS

Intelligibility was reduced for the PD group in comparison to the control group only in the habitual condition. All clear speech variants significantly improved intelligibility above habitual levels for the PD group, with OE maximizing intelligibility, followed by the SC and HI conditions. Both groups rated speaking effort to be significantly higher for both the OE and HI conditions versus the SC and habitual conditions.

DISCUSSION

For speakers with PD, all clear speech variants increased intelligibility to a level comparable to that of healthy controls. All clear speech variants were also associated with higher levels of speaking effort than habitual speech for the speakers with PD. Clinically, findings suggest that clear speech training programs consider using the instruction "overenunciate" for maximizing intelligibility. Future research is needed to identify if high levels of speaking effort elicited by the clear speech variants affect long-term sustainability of the intelligibility benefit.

Attentional Demand of Motor Speech Encoding: Evidence From Parkinson's Disease

PURPOSE

While the involvement of attention in utterance planning is well established at the conceptual and lexical levels, the attentional demands of postlexical processes are still debated. This study investigates the involvement of attentional resources on motor speech encoding during utterance production in the context of Parkinson's disease (PD), a population allowing to assess if the attentional demands observed in a dual-task paradigm (the dual-task costs [DTCs]) are explained by postlexical difficulties and not solely by executive impairment.

METHOD

Speech production was analyzed in a dual-task paradigm with 30 participants presenting with motor speech disorders due to hypokinetic dysarthria in the context of PD. The dual-task comprised an automatic speech task in which participants recited the days of the week and two nonverbal tasks evaluating processing speed and inhibition. The severity of dysarthria and performance in several executive tests (inhibition, verbal fluency, and cognitive shifting) were used as potential predictors of the DTCs.

RESULTS

Individuals with PD exhibited a DTC on the nonverbal tasks and on the speech task when the secondary task was inhibition (the most difficult one). Additionally, the severity of dysarthria and a poorer performance in cognitive shifting predicted a more severe DTC on speech rate. Finally, modulation of the magnitude of the DTCs was observed, depending on the difficulty of the nonverbal secondary task.

CONCLUSION

The results suggest that, in PD, postlexical processes require attentional resources and cognitive shifting is related to dual-task performance in speech.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21265893.

Speaking with a KN95 face mask: a within-subjects study on speaker adaptation and strategies to improve intelligibility

Mask-wearing during the COVID-19 pandemic has prompted a growing interest in the functional impact of masks on speech and communication. Prior work has shown that masks dampen sound, impede visual communication cues, and reduce intelligibility. However, more work is needed to understand how speakers change their speech while wearing a mask and to identify strategies to overcome the impact of wearing a mask. Data were collected from 19 healthy adults during a single in-person session. We investigated the effects of wearing a KN95 mask on speech intelligibility, as judged by two speech-language pathologists, examined speech kinematics and acoustics associated with mask-wearing, and explored KN95 acoustic filtering. We then considered the efficacy of three speaking strategies to improve speech intelligibility: Loud, Clear, and Slow speech. To inform speaker strategy recommendations, we related findings to self-reported speaker effort. Results indicated that healthy speakers could compensate for the presence of a mask and achieve normal speech intelligibility. Additionally, we showed that speaking loudly or clearly-and, to a lesser extent, slowly-improved speech intelligibility. However, using these strategies may require increased physical and cognitive effort and should be used only when necessary. These results can inform recommendations for speakers wearing masks, particularly those with communication disorders (e.g., dysarthria) who may struggle to adapt to a mask but can respond to explicit instructions. Such recommendations may further help non-native speakers and those communicating in a noisy environment or with listeners with hearing loss.

Practice Mediates Bidirectional Dual-Task Interference When Performing a Novel Sequential Nonword Repetition Task

Introduction The current study examined the extent to which practice amount mediates dual-task interference patterns associated with concurrent performance of a novel speech task and attention-demanding visuomotor task. Method A Sequential Nonword Repetition Task was used to examine the effect of practice on interference associated with concurrent performance of a Visuomotor Pursuit Task. Twenty-five young adult participants were assigned to either an Extended Practice Group or a Limited Practice Group and performed a novel Sequential Nonword Repetition Task in isolation and while performing a concurrent visuomotor pursuit rotor task. Results Participants in the Limited Practice Group who were afforded a limited amount of practice exhibited dual-task interference (i.e., dual-task performance reductions) for both the speech and visuomotor tasks (i.e., bidirectional dual-task interference). Conversely, participants in the Extended Practice Group who were afforded extended practice exhibited little-to-no observable dual-task interference on the nonword repetition task. Conclusion Data from the current investigation suggest that the amount of initial practice mediates the degree of dual-task interference observed when a novel speech production task is performed with an attention-demanding Visuomotor Pursuit Task. Supplemental Material https://doi.org/10.23641/asha.14608071.