Loudness perception and speech intensity control in Parkinson's disease

Speech Amplification Device Usage for the Management of Hypophonia: A Survey of Speech-Language Pathologists

PURPOSE

The purpose of this study was to survey speech-language pathologists (SLPs) who assess and treat people with Parkinson's disease (PD) to gather insights into their decision making regarding their use or potential use of speech amplification technology for the management of hypophonia.

METHOD

A total of 111 SLPs who were currently practicing in the United States or Canada and had experience working with clients with PD for at least 2 years completed an anonymous Qualtrics survey. Questions were designed to probe the following areas: (a) degree of familiarity with amplification devices as a form of treatment for PD, (b) attitudes and perceptions of the implementation of these devices for PD, and (c) factors that influence the clinical decision to prescribe such devices.

RESULTS

Most participants (75; 71%) reported they had considered prescribing a device to at least one client with PD. When asked at which stages of speech or voice impairment they would consider the use of an amplification device for clients with PD, the most common response was for clients with moderate or severe hypophonia who were not stimulable for louder speech. However, 36 (32%) respondents indicated they would also consider an amplification device for clients who were stimulable for louder speech with severe hypophonia. When asked to rank the most important factors they would weigh when considering the prescription of an amplification device, they ranked the client's preference and comfort level as the most important consideration.

CONCLUSION

This study provides valuable clinical insights regarding how SLPs can approach utilizing speech amplification devices in the therapy environment.

Clinical Insights Into the Use of Speech Amplification Devices for Managing Hypophonia: Interviews With Speech-Language Pathologists

PURPOSE

The purpose of this qualitative interview study was to identify themes regarding considerations in the usage of speech amplification device usage for people with Parkinson's disease (PD) and hypophonia from the perspective of speech-language pathologists (SLPs).

METHOD

Eligible participants included SLPs currently practicing in the United States or Canada with experience working with clients with PD for at least 2 years. Ten SLPs participated in 60-min interviews conducted via Zoom. A semistructured interview guide was created prior to the interviews. The interviews were transcribed following their completion, and an iterative coding process was used to identify themes using thematic analysis.

RESULTS

Three main themes were identified from the interviews. The first theme encapsulated how clinicians described amplification devices as a potential treatment tool, which highlighted the nuances that may impact selecting an amplification device as a treatment option such as increased hypophonia or dysarthria severity and cognitive decline. The second theme highlighted how device selection depends on the individual needs of the user. Individual client characteristics (such as disease symptoms and individual needs and preferences) may impact the choice of amplification device. The last theme outlined the importance of involving family members in all stages of device use and involving other health care team members on a case-by-case basis.

CONCLUSIONS

The insights provided by the SLP participants help to understand the clinical decisions that are made when determining device candidacy, selecting a device, and evaluating device success. These insights can be used to improve research studies of augmentative management of hypophonia and guide more personalized management decisions.

Oral-diadochokinesis between Parkinson's disease and neurotypical elderly among Malaysian-Malay speakers

BACKGROUND

Parkinson's disease (PD) has an impact on speech production, manifesting in various ways including alterations in voice quality, challenges in articulating sounds and a decrease in speech rate. Numerous investigations have been conducted to ascertain the oral-diadochokinesis (O-DDK) rate in individuals with PD. However, the existing literature lacks exploration of such O-DDK rates in Malaysia and does not provide consistent evidence regarding the advantage of real-word repetition.

AIMS

To explore the effect of gender, stimuli type and PD status and their interactions on the O-DDK rates among Malaysian-Malay speakers.

METHODS & PROCEDURES

O-DDK performance of 62 participants (29 individuals with PD and 33 healthy elderly) using a non-word ('pataka'), a Malay real-word ('patahkan') and an English real-word ('buttercake') was audio recorded. The number of syllables produced in 8 s was counted. A hierarchical linear modelling was performed to investigate the effects of stimuli type (non-word, Malay real-word, English real-word), PD status (yes, no), gender (male, female) and their interactions on the O-DDK rate. The model accounted for participants' age as well as the nesting of repeated measurements within participants, thereby providing unbiased estimates of the effects.

OUTCOMES & RESULTS

The stimuli effect was significant (p < 0.0001). Malay real-word showed the lowest O-DDK rate (5.03 ± 0.11 syllables/s), followed by English real-word (5.25 ± 0.11 syllables/s) and non-word (5.42 ± 0.11 syllables/s). Individuals with PD showed a significantly lower O-DDK rate compared to healthy elderly (4.73 ± 0.15 syllables/s vs. 5.74 ± 0.14 syllables/s, adjusted p < 0.001). A subsequent analysis indicated that the O-DDK rate declined in a quadratic pattern. However, neither gender nor age effects were observed. Additionally, no significant two-way interactions were found between stimuli type, PD status and gender (all p > 0.05). Therefore, the choice of stimuli type has no or only limited effect considering the use of O-DDK tests in clinical practice for diagnostic purposes.

CONCLUSIONS & IMPLICATIONS

The observed slowness in O-DDK among individuals with PD can be attributed to the impact of the movement disorder, specifically bradykinesia, on the physiological aspects of speech production. Speech-language pathologists can gain insights into the impact of PD on speech production and tailor appropriate intervention strategies to address the specific needs of individuals with PD according to disease stages.

WHAT THIS PAPER ADDS

What is already known on this subject The observed slowness in O-DDK rates among individuals with PD may stem from the movement disorder's effects on the physiological aspects of speech production, particularly bradykinesia. However, there is a lack of consistent evidence regarding the influence of real-word repetition and how O-DDK rates vary across different PD stages. What this study adds to existing knowledge The O-DDK rates decline in a quadratic pattern as the PD progresses. The research provides insights into the advantage of real-word repetition in assessing O-DDK rates, with Malay real-word showing the lowest O-DDK rate, followed by English real-word and non-word. What are the potential or actual clinical implications of this work? Speech-language pathologists can better understand the evolving nature of speech motor impairments as PD progresses. This insight enables them to design targeted intervention strategies that are sensitive to the specific needs and challenges associated with each PD stage. This finding can guide clinicians in selecting appropriate assessment tools for evaluating speech motor function in PD patients.

Sex Differences in the Speech of Persons With and Without Parkinson's Disease

BACKGROUND

Sex differences are apparent in the prevalence and the clinical presentation of Parkinson's disease (PD), but their effects on speech have been less studied.

METHOD

Speech acoustics of persons with (34 females and 34 males) and without (age- and sex-matched) PD were examined, assessing the effects of PD diagnosis and sex on ratings of dysarthria severity and acoustic measures of phonation (fundamental frequency standard deviation, smoothed cepstral peak prominence), speech rate (net syllables per second, percent pause ratio), and articulation (articulatory-acoustic vowel space, release burst precision).

RESULTS

Most measures were affected by PD (dysarthria severity, fundamental frequency standard deviation) and sex (smoothed cepstral peak prominence, net syllables per second, percent pause ratio, articulatory-acoustic vowel space), but without interactions between them. Release burst precision was differentially affected by sex in PD. Relative to those without PD, persons with PD produced fewer plosives with a single burst: females more frequently produced multiple bursts, whereas males more frequently produced no burst at all.

CONCLUSIONS

Most metrics did not indicate that speech production is differentially affected by sex in PD. Sex was, however, associated with disparate effects on release burst precision in PD, which deserves further study.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.24388666.

Dysphagia in Parkinson Disease: Part I - Pathophysiology and Diagnostic Practices

Purpose of Review

Dysphagia affects the majority of individuals with Parkinson disease (PD) and is not typically diagnosed until later in disease progression. This review will cover the current understanding of PD pathophysiology, and provides an overview of dysphagia in PD including diagnostic practices, gaps in knowledge, and future directions.

Recent Findings

Many non-motor and other motor signs of PD appear in the prodrome prior to the manifestation of hall- mark signs and diagnosis. While dysphagia often presents already in the prodrome, it is not routinely addressed in standard neurology examinations.

Summary

Dysphagia in PD can result in compromised efficiency and safety of swallowing, which significantly contributes to malnutrition and dehydration, decrease quality of life, and increase mortality. The heterogeneous clinical presentation of PD complicates diagnostic procedures which often leads to delayed treatment. Research has advanced our knowledge of mechanisms underlying PD, but dysphagia is still largely understudied, especially in the prodromal stage.

Aberrant neurophysiological signaling associated with speech impairments in Parkinson's disease

Difficulty producing intelligible speech is a debilitating symptom of Parkinson's disease (PD). Yet, both the robust evaluation of speech impairments and the identification of the affected brain systems are challenging. Using task-free magnetoencephalography, we examine the spectral and spatial definitions of the functional neuropathology underlying reduced speech quality in patients with PD using a new approach to characterize speech impairments and a novel brain-imaging marker. We found that the interactive scoring of speech impairments in PD (N = 59) is reliable across non-expert raters, and better related to the hallmark motor and cognitive impairments of PD than automatically-extracted acoustical features. By relating these speech impairment ratings to neurophysiological deviations from healthy adults (N = 65), we show that articulation impairments in patients with PD are associated with aberrant activity in the left inferior frontal cortex, and that functional connectivity of this region with somatomotor cortices mediates the influence of cognitive decline on speech deficits.

Impaired perceptual phonetic plasticity in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative condition primarily associated with its motor consequences. Although much of the focus within the speech domain has focused on PD's consequences for production, people with PD have been shown to differ in the perception of emotional prosody, loudness, and speech rate from age-matched controls. The current study targeted the effect of PD on perceptual phonetic plasticity, defined as the ability to learn and adjust to novel phonetic input, both in second language and native language contexts. People with PD were compared to age-matched controls (and, for three of the studies, a younger control population) in tasks of explicit non-native speech learning and adaptation to variation in native speech (compressed rate, accent, and the use of timing information within a sentence to parse ambiguities). The participants with PD showed significantly worse performance on the task of compressed rate and used the duration of an ambiguous fricative to segment speech to a lesser degree than age-matched controls, indicating impaired speech perceptual abilities. Exploratory comparisons also showed people with PD who were on medication performed significantly worse than their peers off medication on those two tasks and the task of explicit non-native learning.

What Can Altered Auditory Feedback Paradigms Tell Us About Vocal Motor Control in Individuals With Voice Disorders?

Purpose

The goal of this review article is to provide a summary of the progression of altered auditory feedback (AAF) as a method to understand the pathophysiology of voice disorders. This review article focuses on populations with voice disorders that have thus far been studied using AAF, including individuals with Parkinson's disease, cerebellar degeneration, hyperfunctional voice disorders, vocal fold paralysis, and laryngeal dystonia. Studies using AAF have found that individuals with Parkinson's disease, cerebellar degeneration, and laryngeal dystonia have hyperactive auditory feedback responses due to differing underlying causes. In persons with PD, the hyperactivity may be a compensatory mechanism for atypically weak feedforward motor control. In individuals with cerebellar degeneration and laryngeal dystonia, the reasons for hyperactivity remain unknown. Individuals with hyperfunctional voice disorders may have auditory-motor integration deficits, suggesting atypical updating of feedforward motor control.

Conclusions

These findings have the potential to provide critical insights to clinicians in selecting the most effective therapy techniques for individuals with voice disorders. Future collaboration between clinicians and researchers with the shared objective of improving AAF as an ecologically feasible and valid tool for clinical assessment may provide more personalized therapy targets for individuals with voice disorders.

Speech Rate Mediated Vowel and Stop Voicing Distinctiveness in Parkinson's Disease

Purpose The purpose of this study was to quantify changes in acoustic distinctiveness in two groups of talkers with Parkinson's disease as they modify across a wide range of speaking rates. Method People with Parkinson's disease with and without deep brain stimulation and older healthy controls read 24 carrier phrases at different speech rates. Target nonsense words in the carrier phrases were designed to elicit stop consonants and corner vowels. Participants spoke at seven self-selected speech rates from very slow to very fast, elicited via magnitude production. Speech rate was measured in absolute words per minute and as a proportion of each talker's habitual rate. Measures of segmental distinctiveness included a temporal consonant measure, namely, voice onset time, and a spectral vowel measure, namely, vowel articulation index. Results All talkers successfully modified their rate of speech from slow to fast. Talkers with Parkinson's disease and deep brain stimulation demonstrated greater baseline speech impairment and produced smaller proportional changes at the fast end of the continuum. Increasingly slower speaking rates were associated with increased temporal contrasts (voice onset time) but not spectral contrasts (vowel articulation). Faster speech was associated with decreased contrasts in both domains. Talkers with deep brain stimulation demonstrated more aberrant productions across all speaking rates. Conclusions Findings suggest that temporal and spectral segmental distinctiveness are asymmetrically affected by speaking rate modifications in Parkinson's disease. Talkers with deep brain stimulation warrant further investigation with regard to speech changes they make as they adjust their speaking rate.

Impaired Timing of Speech-Related Neurons in the Subthalamic Nucleus of Parkinson Disease Patients Suffering Speech Disorders

BACKGROUND

Our previous study found degradation to subthalamic neuronal encoding of speech features in Parkinson disease (PD) patients suffering from speech disorders.

OBJECTIVE

To find how timing of speech-related neuronal firing changes in PD patients with speech disorders compared to PD patients without speech disorders.

METHODS

During the implantation of deep brain stimulator (DBS), we recorded the activity of single neurons in the subthalamic nucleus (STN) of 18 neurosurgical patients with PD while they articulated, listened to, or imagined articulation of 5 vowel sounds, each following a beep. We compared subthalamic activity of PD patients with (n = 10) vs without speech disorders.

RESULTS

In this comparison, patients with speech disorders had longer reaction times and shorter lengths of articulation. Their speech-related neuronal activity preceding speech onset (planning) was delayed relative to the beep, but the time between this activity and the emission of speech sound was similar. Notwithstanding, speech-related neuronal activity following the onset of speech (feedback) was delayed when computed relative to the onset. Only in these patients was the time lag of planning neurons significantly correlated with the reaction time. Neuronal activity in patients with speech disorders was delayed during imagined articulation of vowel sounds but earlier during speech perception.

CONCLUSION

Our findings indicate that longer reaction times in patients with speech disorders are due to STN or earlier activity of the speech control network. This is a first step in locating the source(s) of PD delays within this network and is therefore of utmost importance for future treatment of speech disorders.

Single Word Intelligibility of Individuals with Parkinson's Disease in Noise: Pre-Specified Secondary Outcome Variables from a Randomized Control Trial (RCT) Comparing Two Intensive Speech Treatments (LSVT LOUD vs. LSVT ARTIC)

The majority of people with Parkinson's disease (PD) experience both prosodic changes (reduced vocal volume, reduced pitch range) and articulatory changes (imprecise articulation) that often limit speech intelligibility and may contribute to significant declines in quality of life. We conducted a randomized control trial comparing two intensive treatments, voice (LSVT LOUD) or articulation (LSVT ARTIC) to assess single word intelligibility in the presence of background noise (babble and mall). Participants (64 PD and 20 Healthy) read words from the diagnostic rhyme test (DRT), an ANSI Standard for measuring intelligibility of speech, before and after one month (treatment or no treatment). Teams of trained listeners blindly rated the data. Speech intelligibility of words in the presence of both noise conditions improved in PD participants who had LSVT LOUD compared to the groups that had LSVT ARTIC or no treatment. Intensive speech treatment targeting prominent prosodic variables in LSVT LOUD had a positive effect on speech intelligibility at the single word level in PD.

HiCommunication as a novel speech and communication treatment for Parkinson's disease: A feasibility study

INTRODUCTION

Speech and communication problems are common in Parkinson's disease (PD) and can result in social withdrawal and reduced quality of life. Intervention may improve symptoms but transfer and maintenance remain challenging for many. Access to treatment may also be limited. Group intervention incorporating principles for experience-dependent plasticity may address these challenges. The aim of this study was to develop and study feasibility aspects of a new intervention program for group training of speech and communication in people with PD.

MATERIALS & METHODS

Development and content of the program called HiCommunication is described. Core target areas are voice, articulation, word-finding and memory. Five participants with mild-moderate PD completed this feasibility trial. Attendance rate and possible adverse events as well as the participants' experiences were documented. A speech recording and dysarthria testing were completed to study feasibility of the assessment procedure and evaluate possible changes in voice sound level and intelligibility.

RESULTS

Attendance rate was 89%. No adverse events occurred. Participants reported a positive experience and limited fatigue. Assessment was completed in approximately 30 min and was well tolerated. Four of five participants had an increased voice sound level during text-reading postintervention and mean intelligibility improved.

CONCLUSIONS

Results indicate that HiCommunication is feasible for people with mild-moderate PD. The program was appreciated and well tolerated. Positive outcomes regarding voice sound level and intelligibility were observed; however, the number of participants was very limited. The results motivate that effects of HiCommunication are further studied in a randomized controlled trial, which is ongoing.

Evaluation of multi-feature auditory deviance detection in Parkinson's disease: a mismatch negativity study

Behavioral studies on auditory deviance detection in patients with Parkinson's disease (PD) have reported contradictory results. The primary aim of this study was to investigate auditory deviance detection of multiple auditory features in patients with PD by means of objective and reliable electroencephalographic (EEG) measurements. Twelve patients with early-stage PD and twelve age- and gender-matched healthy controls (HCs) were included in this study. Patients with PD participated without their regular dopaminergic medication. All subjects underwent an audiometric screening and performed a passive multi-feature mismatch negativity (MMN) paradigm. Repeated-measures analysis of variance (ANOVA) demonstrated no significant differences between patients with PD and HCs regarding MMN mean amplitude and latency for frequency, duration and gap deviants. Nevertheless, a trend towards increased MMN mean amplitude and latency was found in response to intensity deviants in patients with PD compared to HCs. Increased intensity MMN amplitude may indicate that more neural resources are allocated to the processing of intensity deviances in patients with PD compared to HCs. The interpretation of this intensity-specific MMN alteration is further discussed in the context of a compensatory mechanism for auditory intensity processing and involuntary attention switching in PD.

Attitudes Toward the Use of Voice-Assisted Technologies Among People With Parkinson Disease: Findings From a Web-Based Survey

BACKGROUND

Speech problems are common in people living with Parkinson disease (PD), limiting communication and ultimately affecting their quality of life. Voice-assisted technology in health and care settings has shown some potential in small-scale studies to address such problems, with a retrospective analysis of user reviews reporting anecdotal communication effects and promising usability features when using this technology for people with a range of disabilities. However, there is a need for research to establish users' perspectives on the potential contribution of voice-assisted technology for people with PD.

OBJECTIVE

This study aims to explore the attitudes toward the use of voice-assisted technology for people with PD.

METHODS

A survey was approved for dissemination by a national charity, Parkinson's UK, to be completed on the web by people living with the condition. The survey elicited respondent demographics, PD features, voice difficulties, digital skill capability, smart technology use, voice-assisted technology ownership and use, confidentiality, and privacy concerns. Data were analyzed using descriptive statistics and summative content analysis of free-text responses.

RESULTS

Of 290 participants, 79.0% (n=229) indicated that they or others had noticed changes in their speech or voice because of the symptoms of their condition. Digital skills and awareness were reported on 11 digital skills such as the ability to find a website you have visited before. Most participants (n=209, 72.1%) reported being able to perform at least 10 of these 11 tasks. Similarly, of 70.7% (n=205) participants who owned a voice-assisted device, most of them (166/205, 80.9%) used it regularly, with 31.3% (52/166) reporting that they used the technology specifically to address the needs associated with their PD. Of these 166 users, 54.8% (n=91) sometimes, rarely, or never had to repeat themselves when using the technology. When asked about speech changes since they started using it, 25% (27/108) of participants noticed having to repeat themselves less and 14.8% (16/108) perceived their speech to be clearer. Of the 290 respondents, 90.7% (n=263) were not concerned, or only slightly concerned, about privacy and confidentiality.

CONCLUSIONS

Having been added to the homes of Western society, domestic voice assist devices are now available to assist those with communication problems. People with PD reported a high digital capability, albeit those who responded to a web-based survey. Most people have embraced voice-assisted technology, find it helpful and usable, and some have found benefit to their speech. Speech and language therapists may have a virtual ally that is already in the patient's home to support future therapy provision.

Neurophysiological investigation of auditory intensity dependence in patients with Parkinson's disease

There is accumulating evidence for auditory dysfunctions in patients with Parkinson's disease (PD). Moreover, a possible relationship has been suggested between altered auditory intensity processing and the hypophonic speech characteristics in PD. Nonetheless, further insight into the neurophysiological correlates of auditory intensity processing in patients with PD is needed primarily. In the present study, high-density EEG recordings were used to investigate intensity dependence of auditory evoked potentials (IDAEPs) in 14 patients with PD and 14 age- and gender-matched healthy control participants (HCs). Patients with PD were evaluated in both the on- and off-medication states. HCs were also evaluated twice. Significantly increased IDAEP of the N1/P2 was demonstrated in patients with PD evaluated in the on-medication state compared to HCs. Distinctive results were found for the N1 and P2 component. Regarding the N1 component, no differences in latency or amplitude were shown between patients with PD and HCs regardless of the medication state. In contrast, increased P2 amplitude was demonstrated in patients with PD evaluated in the on-medication state compared to the off-medication state and HCs. In addition to a dopaminergic deficiency, deficits in serotonergic neurotransmission in PD were shown based on increased IDAEP. Due to specific alterations of the N1-P2 complex, the current results suggest deficiencies in early-attentive inhibitory processing of auditory input in PD. This interpretation is consistent with the involvement of the basal ganglia and the role of dopaminergic and serotonergic neurotransmission in auditory gating.

A Comparison of Speech Amplification and Personal Communication Devices for Hypophonia

Purpose This study compared the performance of three amplification devices hypothesized to improve speech communication in individuals with hypophonia (HP), as well as to identify individuals' device preferences. Method Twenty-two individuals with HP and their primary communication partners participated in a cross-over design study comparing three different speech amplification devices: a wired portable amplifier (Device A), a wireless stationary amplifier (Device B), and a one-way personal communication system (Device C). Participants attended one laboratory visit followed by 1-week trial periods with each device. At the first visit, HP participants completed speech tasks with and without the devices, in quiet and in noise. Following the in-laboratory test period, participants trialed each device at home for approximately 1 week per device. Following completion of the study, participants indicated whether or not they would like to continue using a device. Results Overall, in the presence of noise, all three devices demonstrated significant improvements in speech-to-noise levels and speech intelligibility compared to no device. A clear device hierarchy emerged such that the personal communication device (Device C) was associated with significantly better speech outcomes compared to the other two devices. The majority of participants elected to continue using a device at the completion of the study. Device preferences, however, did not clearly reflect the objective device hierarchy that was found for the objective speech measures. Each of the three devices was selected as a preferred device by at least three participants at the completion of the study. Conclusion Results from this study demonstrated clear differences in device performance in three distinct forms of amplification devices for individuals with HP. Findings suggest that amplification device use may be beneficial for this clinical population and underscore the potential to improve device availability and device selection criteria in future research. Supplemental Material https://doi.org/10.23641/asha.12735875.

Future Perspectives on the Relevance of Auditory Markers in Prodromal Parkinson's Disease

Research on auditory processing in Parkinson's disease (PD) has recently made substantial progress. At present, evidence has been found for altered auditory processing in the clinical stage of PD. The auditory alterations in PD have been demonstrated with low-cost and non-invasive assessments that are already used in routine clinical practice. Since auditory alterations have been reported early in disease progression, it would be highly relevant to investigate whether auditory markers could be provided in the prodromal stage of PD. In addition, auditory alterations in early stage PD might be modulated by dopaminergic medication. Therefore, the aim of this review is (1) to summarize the literature on auditory processing in PD with a specific focus on the early disease stages, (2) to give future perspectives on which audiological and electrophysiological measurements could be useful in the prodromal stage of PD and (3) to assess the effect of dopaminergic medication on potential auditory markers in the prodromal stage of PD.

Effect of Resonance Tube Technique on Oropharyngeal Geometry and Voice in Individuals with Parkinson's Disease

OBJECTIVE

To verify the immediate effect of the flexible resonance tube vocal technique on the oropharyngeal geometry and vocal acoustic parameters of individuals with Parkinson's disease (PD) and to study the correlation between oropharyngeal geometry and the intensity and fundamental frequency (f0) parameters of the voice.

METHODS

Forty individuals participated-20 with PD and 20 healthy individuals, with a mean age of 60.95 (± 5.69) years. There were 10 men and 10 women in each group. All underwent pharyngometric analysis of the vocal tract and voice acoustics parameters before and after use of the vocal technique with a flexible resonance tube.

RESULTS

After the technique, there was a reduction in pharyngeal cavity volume only in females in the healthy group, a reduction in shimmer values in females in both groups and males in PD group and an improvement in noise parameters in females in the PD group. There was a negative correlation between vocal tract volume and intensity, between f0 and vocal tract volume, between f0 and oropharyngeal junction area, between f0 and oral cavity volume as well as a positive correlation between oral cavity length and f0.

CONCLUSION

The vocal technique with the flexible resonance tube applied to individuals with PD improved the subjects' voice quality in the perceptual and acoustic voice parameters. Regarding the oropharyngeal geometry, it was possible to observe its correlation with the parameters of vocal intensity and frequency in the studied population.

Central auditory processing in parkinsonian disorders: A systematic review

Altered auditory processing has been increasingly recognized as a non-motor feature in parkinsonian disorders. This systematic review provides an overview of behavioral and electrophysiological literature on central auditory processing in patients with Parkinson's disease (PD), multiple system atrophy (MSA) and progressive supranuclear palsy (PSP). A systematic database search was conducted and yielded 88 studies that met the intelligibility criteria. The collected data revealed distinct impairments in a range of central auditory processes in PD, including altered deviance detection of basic auditory features, auditory brainstem processing, auditory gating and selective auditory attention. In contrast to PD, literature on central auditory processing in atypical parkinsonian disorders was relatively scarce, but provided some evidence for impaired central auditory processing in MSA and PSP. The interpretation of these findings is discussed and suggestions for further research are offered.

Auditory Dysfunction in Parkinson's Disease

PD is a progressive and complex neurological disorder with heterogeneous symptomatology. PD is characterized by classical motor features of parkinsonism and nonmotor symptoms and involves extensive regions of the nervous system, various neurotransmitters, and protein aggregates. Extensive evidence supports auditory dysfunction as an additional nonmotor feature of PD. Studies indicate a broad range of auditory impairments in PD, from the peripheral hearing system to the auditory brainstem and cortical areas. For instance, research demonstrates a higher occurrence of hearing loss in early-onset PD and evidence of abnormal auditory evoked potentials, event-related potentials, and habituation to novel stimuli. Electrophysiological data, such as auditory P3a, also is suggested as a sensitive measure of illness duration and severity. Improvement in auditory responses following dopaminergic therapies also indicates the presence of similar neurotransmitters (i.e., glutamate and dopamine) in the auditory system and basal ganglia. Nonetheless, hearing impairments in PD have received little attention in clinical practice so far. This review summarizes evidence of peripheral and central auditory impairments in PD and provides conclusions and directions for future empirical and clinical research. © 2020 International Parkinson and Movement Disorder Society.

The Relationship Between Speech Perceptual Discrimination and Speech Production in Parkinson's Disease

Purpose We recently demonstrated that individuals with Parkinson's disease (PD) respond differentially to specific altered auditory feedback parameters during speech production. Participants with PD respond more robustly to pitch and less robustly to formant manipulations compared to control participants. In this study, we investigated whether differences in perceptual processing may in part underlie these compensatory differences in speech production. Methods Pitch and formant feedback manipulations were presented under 2 conditions: production and listening. In the production condition, 15 participants with PD and 15 age- and gender-matched healthy control participants judged whether their own speech output was manipulated in real time. During the listening task, participants judged whether paired tokens of their previously recorded speech samples were the same or different. Results Under listening, 1st formant manipulation discrimination was significantly reduced for the PD group compared to the control group. There was a trend toward better discrimination of pitch in the PD group, but the group difference was not significant. Under the production condition, the ability of participants with PD to identify pitch manipulations was greater than that of the controls. Conclusion The findings suggest perceptual processing differences associated with acoustic parameters of fundamental frequency and 1st formant perturbations in PD. These findings extend our previous results, indicating that different patterns of compensation to pitch and 1st formant shifts may reflect a combination of sensory and motor mechanisms that are differentially influenced by basal ganglia dysfunction.

Systematic Audiological Assessment of Auditory Functioning in Patients With Parkinson's Disease

Purpose Alterations in primary auditory functioning have been reported in patients with Parkinson's disease (PD). Despite the current findings, the pathophysiological mechanisms underlying these alterations remain unclear, and the effect of dopaminergic medication on auditory functioning in PD has been explored insufficiently. Therefore, this study aimed to systematically investigate primary auditory functioning in patients with PD by using both subjective and objective audiological measurements. Method In this case-control study, 25 patients with PD and 25 age-, gender-, and education-matched healthy controls underwent an audiological test battery consisting of tonal audiometry, short increment sensitivity index, otoacoustic emissions (OAEs), and speech audiometry. Patients with PD were tested in the on- and off-medication states. Results Increased OAE amplitudes were found when patients with PD were tested without dopaminergic medication. In addition, speech audiometry in silence and multitalker babble noise demonstrated higher phoneme scores for patients with PD in the off-medication condition. The results showed no differences in auditory functioning between patients with PD in the on-medication condition and healthy controls. No effect of disease stage or motor score was evident. Conclusions This study provides evidence for a top-down involvement in auditory processing in PD at both central and peripheral levels. Most important, the increase in OAE amplitude in the off-medication condition in PD is hypothesized to be linked to a dysfunction of the olivocochlear efferent system, which is known to have an inhibitory effect on outer hair cell functioning. Future studies may clarify whether OAEs may facilitate an early diagnosis of PD.

Effects of Concurrent Manual Task Performance on Connected Speech Acoustics in Individuals With Parkinson Disease

Purpose Prior investigations suggest that simultaneous performance of more than 1 motor-oriented task may exacerbate speech motor deficits in individuals with Parkinson disease (PD). The purpose of the current investigation was to examine the extent to which performing a low-demand manual task affected the connected speech in individuals with and without PD. Method Individuals with PD and neurologically healthy controls performed speech tasks (reading and extemporaneous speech tasks) and an oscillatory manual task (a counterclockwise circle-drawing task) in isolation (single-task condition) and concurrently (dual-task condition). Results Relative to speech task performance, no changes in speech acoustics were observed for either group when the low-demand motor task was performed with the concurrent reading tasks. Speakers with PD exhibited a significant decrease in pause duration between the single-task (speech only) and dual-task conditions for the extemporaneous speech task, whereas control participants did not exhibit changes in any speech production variable between the single- and dual-task conditions. Conclusions Overall, there were little to no changes in speech production when a low-demand oscillatory motor task was performed with concurrent reading. For the extemporaneous task, however, individuals with PD exhibited significant changes when the speech and manual tasks were performed concurrently, a pattern that was not observed for control speakers. Supplemental Material https://doi.org/10.23641/asha.8637008.

Relationship Between Respiratory Sensory Perception, Speech, and Swallow in Parkinson's Disease

Background

It has been suggested that sensory impairments contribute significantly to the motor deficits secondary to impaired sensorimotor integration in Parkinson's disease. Speech and swallowing are likely to become disordered in PD, and there is evidence that impaired upper airway sensation also contributes to these disorders.

Objectives

The goal of this study was to investigate the relationship between perception of general respiratory sensation, speech, and swallowing in PD.

Methods

Thirteen people with PD and 14 age-equivalent controls volunteered to participate. Randomized blocks of inspiratory resistive loads were delivered, and participants gauged the magnitude of the loads using a modified Borg scale. The magnitude estimates were then compared to results of speech and swallowing evaluations using multivariate analysis of variance and a stepwise linear regression model.

Results

There was a significant overall interaction between the participant group (PD versus control) and respiratory load (F [10, 300] = 2.138; P = .022). A significant regression equation containing a predictor speech variable respiratory rating was found (F [1,22] = 6.946), P = .023), with a moderate effect size of R² = .387.

Conclusions

People with PD have blunted perception of respiratory resistive loads when compared with age-equivalent healthy adults. Results also suggest that blunted ME of resistive loads could contribute to changes in respiratory drive for speech (i.e., loudness).

Speech treatment in Parkinson's disease: Randomized controlled trial (RCT)

BACKGROUND

As many as 89% of people with Parkinson's disease (PD) develop speech disorders.

OBJECTIVES

This randomized controlled trial evaluated two speech treatments for PD matched in intensive dosage and high-effort mode of delivery, differing in subsystem target: voice (respiratory-laryngeal) versus articulation (orofacial-articulatory).

METHODS

PD participants were randomized to 1-month LSVT LOUD (voice), LSVT ARTIC (articulation), or UNTXPD (untreated) groups. Speech clinicians specializing in PD delivered treatment. Primary outcome was sound pressure level (SPL) in reading and spontaneous speech, and secondary outcome was participant-reported Modified Communication Effectiveness Index (CETI-M), evaluated at baseline, 1, and 7 months. Healthy controls were matched by age and sex.

RESULTS

At baseline, the combined PD group (n = 64) was significantly worse than healthy controls (n = 20) for SPL (P < 0.05) and CETI-M (P = 0.0001). At 1 and 7 months, SPL between-group comparisons showed greater improvements for LSVT LOUD (n = 22) than LSVT ARTIC (n = 20; P < 0.05) and UNTXPD (n = 22; P < 0.05). Sound pressure level differences between LSVT ARTIC and UNTXPD at 1 and 7 months were not significant (P > 0.05). For CETI-M, between-group comparisons showed greater improvements for LSVT LOUD and LSVT ARTIC than UNTXPD at 1 month (P = 0.02; P = 0.02). At 7 months, CETI-M between-group differences were not significant (P = 0.08). Within-group CETI-M improvements for LSVT LOUD were maintained through 7 months (P = 0.0011).

CONCLUSIONS

LSVT LOUD showed greater improvements than both LSVT ARTIC and UNTXPD for SPL at 1 and 7 months. For CETI-M, both LSVT LOUD and LSVT ARTIC improved at 1 month relative to UNTXPD. Only LSVT LOUD maintained CETI-M improvements at 7 months. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Stimulation of the subparafascicular thalamic nucleus modulates dopamine release in the inferior colliculus of rats

Although dopamine is commonly studied for its role in incentive motivation, cognition, and various neuropsychiatric disorders, evidence from Parkinson's disease (PD) patients that present auditory deficits suggest that dopamine is also involved in central auditory processing. It has been recently discovered that the subparafascicular thalamic nucleus (SPF) sends dopaminergic projections to the inferior colliculus (IC), an important convergence hub for the ascending and descending auditory pathways. In the present study, our aim was to provide neurochemical evidence that activation of SPF neurons evokes dopamine release in the IC of anesthetized rats using fast-scan cyclic and paired pulse voltammetry in combination with carbon fiber microelectrodes. Electrical stimulation of the SPF (60 and 90 Hz) evoked dopamine release in the IC in a frequency-dependent manner, with higher frequencies evoking greater amplitude dopamine responses. Optogenetic-evoked dopamine responses were similar to the effects of electrical stimulation suggesting that electrical stimulation-evoked dopamine release was not due to nonspecific activation of fibers of passage, but rather to activation of SPF cells projecting to the IC. Selective dopamine reuptake blockade enhanced the evoked dopamine response, while selective blockade of serotonin did not, confirming the selectivity of the neurochemical recordings to dopamine. Therefore, the SPF neuronal pathway functionally mediates dopamine release in the IC and thus may be involved in auditory processing deficits associated with PD.

Loudness Perception of Pure Tones in Parkinson's Disease

PURPOSE

Reduced intensity is a hallmark of speech production in Parkinson's disease (PD). Previous work has examined the perception of intensity in PD to explain these speech deficits. This study reports loudness ratings of pure tones by individuals with PD and controls, all with normal thesholds for older adults.

METHOD

Twenty individuals with PD and 23 age- and sex-matched controls rated the loudness of pure tones from 1 (very soft) to 7 (uncomfortably loud). Tones at 500, 750, 1000, 2000, and 4000 Hz were presented from 35 to 80 dB HL (or until a rating of 7 was given). A mixed-model analysis of variance was performed on ratings to assess the effects of group, frequency, sound intensity, and ear. Loudness growth slopes were determined for each participant and analyzed by group.

RESULTS

The mean loudness growth slopes of the control and PD groups did not significantly differ.

CONCLUSIONS

No difference was found in loudness growth slopes in response to externally generated tones in PD. This is in contrast with the findings of previous studies of self-generated speech and externally presented speech. The underlying causes for impaired perception and production of loudness in PD require further investigation.

Drooling in Parkinson's Disease: Evidence of a Role for Divided Attention

Drooling is a frequently reported symptom in Parkinson's Disease (PD) with significant psychosocial impact and negative health consequences including silent aspiration of saliva with the associated risk of respiratory infections. It is suggested that in PD drooling is associated with inefficient oropharyngeal swallowing which reduces the effective clearance of saliva rather than hyper-salivation. This is compounded by unintended mouth opening and flexed posture increasing anterior loss of saliva. It is reported to occur most frequently during cognitively distracting concurrent tasks suggesting an impact from divided attention in a dual-task situation. However, this supposition has not been systematically examined. This study assessed whether frequency of saliva swallows reduced, and drooling severity and frequency increased, when people with PD engaged in a cognitively distracting task. 18 patients with idiopathic PD reporting daytime drooling on the Unified Parkinson's Disease Rating Scale (UPDRS) were recruited. They completed the Radboud Oral Motor Inventory for PD saliva questionnaire and the Montreal Cognitive Assessment. UPDRS drooling score, disease stage, duration, gender, and age were recorded. Swallow frequency and drooling severity and frequency were measured at rest and during a distracting computer-based language task. There was no significant difference between drooling severity at rest and during distraction (Wilcoxon signed rank test z = - 1.724, p = 0.085). There was a significant difference between at rest and distraction conditions for both drooling frequency (Wilcoxon signed rank test z = - 2.041, p = 0.041) and swallow frequency (Wilcoxon signed rank test z = - 3.054, p = 0.002). Participants swallowed less frequently and drooled more often during the distraction task. The frequency of saliva swallows and drooling are affected by divided attention in a dual-task paradigm. Further studies are needed to explore the exact role of attention in saliva management and the clinical applications in assessment and treatment.

Is there an order of loss of sounds in speakers with Parkinson's disease?

Influential reports on speech changes in people with Parkinson's disease (PD; Logemann et al., 1978, 1981) reported a posterior to anterior pattern of loss of speech sound accuracy. These claims have never been examined. In a partial replication of Logemann et al.'s work, we examined whether posterior lingual sounds are most affected in people with Parkinson's disease, followed by anterior lingual sounds and then labial sounds. Ninety-nine people with PD (age: mean 70.7, SD 8.46; time since diagnosis: mean 6.97, SD 6.2) with mild to severe overall motor symptoms (Hoehn and Yahr stages 1-5, median 2.5) completed a diagnostic intelligibility test. This was scored by 60 listeners unfamiliar with PD and dysarthric speech. We calculated the proportion of posterior versus anterior lingual versus labial sounds misrecognized by the listeners. We compared profiles of misperceived sounds within and across Hoehn and Yahr stages of severity and in relation to Unified Parkinson's Disease Rating Scale (UPDRS) and speech intelligibility scores. Speech accuracy declined significantly in relation to overall motor impairment for labial and anterior lingual sounds but not for velar sounds. Speech sound accuracy was strongly associated with intelligibility outcomes (p = < 0.01). Contrary to previous assertions, there was no evidence supporting the existence of a posterior to anterior order of 'loss' of oral speech sounds in people with PD, nor an interaction of anterior-posterior speech profile changes with Hoehn and Yahr stage. Findings support the notion that a common underlying impairment of movement downscaling affects all sounds similarly and simultaneously in PD from the start.

Swallowing in Parkinson's disease: clinical issues and management

Changes to swallowing affect most people with Parkinson's disease (PD). Changes may not initially exercise a decisive impact, but can later pose significant threats to nutritional, hydration and respiratory health and psychosocial quality of life. This review, from a largely clinical viewpoint, outlines the nature of changes in PD and considers the issue of how many people are affected and in what ways. It outlines main approaches to assessment and management, with an emphasis on aspects relevant to PD. Dysphagia contributes to drooling in PD. The review therefore also touches on the nature and management of this condition that has its own set of health and psychosocial quality-of-life issues.

Utility and accuracy of perceptual voice and speech distinctions in the diagnosis of Parkinson’s disease, PSP and MSA-P

Aim: To determine if perceptual speech measures distinguish people with Parkinson’s disease (PD), multiple system atrophy with predominant parkinsonism (MSA-P) and progressive supranuclear palsy (PSP). Methods: Speech–language therapists blind to patient characteristics employed clinical rating scales to evaluate speech/voice in 24 people with clinically diagnosed PD, 17 with PSP and 9 with MSA-P, matched for disease duration (mean 4.9 years, standard deviation 2.2). Results: No consistent intergroup differences appeared on specific speech/voice variables. People with PD were significantly less impaired on overall speech/voice severity. Analyses by severity suggested further investigation around laryngeal, resonance and fluency changes may characterize individual groups. Conclusion: MSA-P and PSP compared with PD were distinguished by severity of speech/voice deterioration, but individual speech/voice parameters failed to consistently differentiate groups.

Speech production and sensory impairment in mild Parkinson's disease

Little is known about speech-related sensory systems and the link to speech in Parkinson's disease (PD). This study investigates auditory and somatosensory acuity and their association to speech in PD, using /s/ and /ʃ/ as speech targets. Ten adults with mild PD and ten age- and gender-matched healthy participants performed three tasks. In the auditory task, participants discriminated three aperiodic sounds acoustically modified from /s/ and /ʃ/ and differing in spectral shapes. In the tactile task, they judged the orientation of a dome-shaped grating probe gently touching their tongue tip. Measures of auditory and tactile acuity were determined based on participants' responses. For the production task, participants read a passage and eight sentences with /s/- and /ʃ/-initial words; acoustic contrast between the two sibilants was measured using difference between the average first spectral moments of /s/ and /ʃ/. The PD participants showed reduced auditory acuity of spectral sibilant contrast and reduced tactile acuity of the tongue tip. For speech production, the PD group showed smaller sibilant contrast in the sentence readings, but the difference was not statistically significant. Correlation analyses showed significant correlations between tactile acuity and sibilant contrast for the PD group, but not for auditory task.

Misperceptions and Parkinson's disease

Most of the neurobehavioral aspects of Parkinson's disease have been well established and studied, but many are not well known, and hardly studied. This article focuses on several behavioral abnormalities that are common, and frequently cause difficulty for the patient and family due to lack of recognition as part of the disease. While it is well known that L-Dopa dyskinesias are frequently not recognized or under appreciated by patients, a similar lack of recognition may affect the patient's own speech volume, where their center of gravity is located, whether they are tilted to one side, and their under-recognition of others' emotional displays. In addition, PD patients are often misperceived by others incorrect impression of their emotional and cognitive state based purely on facial expression. These changes and others are briefly reviewed.

The Relationship Between Speech Production and Speech Perception Deficits in Parkinson's Disease

PURPOSE

This study investigated the possible relationship between hypokinetic speech production and speech intensity perception in patients with Parkinson's disease (PD).

METHOD

Participants included 14 patients with idiopathic PD and 14 matched healthy controls (HCs) with normal hearing and cognition. First, speech production was objectified through a standardized speech intelligibility assessment, acoustic analysis, and speech intensity measurements. Second, an overall estimation task and an intensity estimation task were addressed to evaluate overall speech perception and speech intensity perception, respectively. Finally, correlation analysis was performed between the speech characteristics of the overall estimation task and the corresponding acoustic analysis. The interaction between speech production and speech intensity perception was investigated by an intensity imitation task.

RESULTS

Acoustic analysis and speech intensity measurements demonstrated significant differences in speech production between patients with PD and the HCs. A different pattern in the auditory perception of speech and speech intensity was found in the PD group.

CONCLUSIONS

Auditory perceptual deficits may influence speech production in patients with PD. The present results suggest a disturbed auditory perception related to an automatic monitoring deficit in PD.

Prosodic analysis of neutral, stress-modified and rhymed speech in patients with Parkinson's disease

BACKGROUND AND OBJECTIVE

Hypokinetic dysarthria (HD) is a frequent speech disorder associated with idiopathic Parkinson's disease (PD). It affects all dimensions of speech production. One of the most common features of HD is dysprosody that is characterized by alterations of rhythm and speech rate, flat speech melody, and impairment of speech intensity control. Dysprosody has a detrimental impact on speech naturalness and intelligibility.

METHODS

This paper deals with quantitative prosodic analysis of neutral, stress-modified and rhymed speech in patients with PD. The analysis of prosody is based on quantification of monopitch, monoloudness, and speech rate abnormalities. Experimental dataset consists of 98 patients with PD and 51 healthy speakers. For the purpose of HD identification, sequential floating feature selection algorithm and random forests classifier is used. In this paper, we also introduce a concept of permutation test applied in the field of acoustic analysis of dysarthric speech.

RESULTS

Prosodic features obtained from stress-modified reading task provided higher classification accuracies compared to the ones extracted from reading task with neutral emotion demonstrating the importance of stress in speech prosody. Features calculated from poem recitation task outperformed both reading tasks in the case of gender-undifferentiated analysis showing that rhythmical demands can in general lead to more precise identification of HD. Additionally, some gender-related patterns of dysprosody has been observed.

CONCLUSIONS

This paper confirms reduced variation of fundamental frequency in PD patients with HD. Interestingly, increased variability of speech intensity compared to healthy speakers has been detected. Regarding speech rate disturbances, our results does not report any particular pattern. We conclude further development of prosodic features quantifying the relationship between monopitch, monoloudness and speech rate disruptions in HD can have a great potential in future PD analysis.

Evaluation of Speech Amplification Devices in Parkinson's Disease

PURPOSE

The purpose of this study was to evaluate the efficacy of selected speech amplification devices in individuals with hypophonia and idiopathic Parkinson's disease (PD).

METHOD

This study compared the effectiveness of seven devices (ADDvox, BoomVox, ChatterVox, Oticon Amigo, SoniVox, Spokeman, and Voicette) to unamplified speech for 11 participants with PD during conversation in 65-dB SPL multitalker noise, using experience ratings collected from participant questionnaires and speech performance measures (i.e., speech-to-noise ratio [SNR], speech intensity, and intelligibility) obtained from audio recordings.

RESULTS

Compared with unamplified speech, device use increased SNR by 1.07-4.73 dB SPL and speech intensity by 1.1-5.1 dB SPL, and it significantly increased transcribed intelligibility from 13.8% to 58.9%. In addition, the type of device used significantly affected speech performance measures (e.g., BoomVox was significantly higher than most of the other devices for SNR, speech intensity, and intelligibility). However, experience ratings did not always correspond to performance measures.

CONCLUSIONS

This study found preliminary evidence of improved speech performance with device use for individuals with PD. A tentative hierarchy is suggested for device recommendations. Future research is needed to determine which measures will predict long-term device acceptance in PD.

Effect of concurrent walking and interlocutor distance on conversational speech intensity and rate in Parkinson's disease

Previous studies have demonstrated a negative effect of concurrent walking and talking on gait in Parkinson's disease (PD) but there is limited information about the effect of concurrent walking on speech production. The present study examined the effect of sitting, standing, and three concurrent walking tasks (slow, normal, fast) on conversational speech intensity and speech rate in fifteen individuals with hypophonia related to idiopathic Parkinson's disease (PD) and fourteen age-equivalent controls. Interlocuter (talker-to-talker) distance effects and walking speed were also examined. Concurrent walking was found to produce a significant increase in speech intensity, relative to standing and sitting, in both the control and PD groups. Faster walking produced significantly greater speech intensity than slower walking. Concurrent walking had no effect on speech rate. Concurrent walking and talking produced significant reductions in walking speed in both the control and PD groups. In general, the results of the present study indicate that concurrent walking tasks and the speed of concurrent walking can have a significant positive effect on conversational speech intensity. These positive, "energizing" effects need to be given consideration in future attempts to develop a comprehensive model of speech intensity regulation and they may have important implications for the development of new evaluation and treatment procedures for individuals with hypophonia related to PD.

Examining the relationship between speech intensity and self-rated communicative effectiveness in individuals with Parkinson's disease and hypophonia

PURPOSE

To examine the relationship between speech intensity and self-ratings of communicative effectiveness in speakers with Parkinson's disease (PD) and hypophonia. An additional purpose was to evaluate if self-ratings of communicative effectiveness made by participants with PD differed from ratings made by primary communication partners.

METHODS

Thirty participants with PD and 15 healthy older adults completed the Communication Effectiveness Survey. Thirty primary communication partners rated the communicative effectiveness of his/her partner with PD. Speech intensity was calculated for participants with PD and control participants based on conversational utterances.

RESULTS

Results revealed significant differences between groups in conversational speech intensity (p=.001). Participants with PD self-rated communicative effectiveness significantly lower than control participants (p=.000). Correlational analyses revealed a small but non-significant relationship between speech intensity and communicative effectiveness for participants with PD (r=0.298, p=.110) and control participants (r=0.327, p=.234). Self-ratings of communicative effectiveness made participants with PD was not significantly different than ratings made by primary communication partners (p=.20).

CONCLUSIONS

Obtaining information on communicative effectiveness may help to broaden outcome measurement and may aid in the provision of educational strategies. Findings also suggest that communicative effectiveness may be a separate and a distinct construct that cannot necessarily be predicted from the severity of hypophonia.