Comparison of transducers and intraoral placement options for measuring lingua-palatal contact pressure during speech

Performance of Oral Cavity Sensors: A Systematic Review

Technological advancements are enabling new applications within biomedical engineering. As a connection point between the outer environment and the human system, the oral cavity offers unique opportunities for sensing technologies. This paper systematically reviews the performance of measurement systems tested in the human oral cavity. Performance was defined by metrics related to accuracy and agreement estimation. A comprehensive search identifying human studies that reported on the accuracy or agreement of intraoral sensors found 85 research papers. Most of the literature (62%) was in dentistry, followed by neurology (21%), and physical medicine and rehabilitation (12%). The remaining papers were on internal medicine, obstetrics, and aerospace medicine. Most of the studies applied force or pressure sensors (32%), while optical and image sensors were applied most widely across fields. The main challenges for future adoption include the lack of large human trials, the maturity of emerging technologies (e.g., biochemical sensors), and the absence of standardization of evaluation in specific fields. New research should aim to employ robust performance metrics to evaluate their systems and incorporate real-world evidence as part of the evaluation process. Oral cavity sensors offer the potential for applications in healthcare and wellbeing, but for many technologies, more research is needed.

Changes in lingual-alveolar contact pressure during speech over six months in amyotrophic lateral sclerosis

PURPOSE

This study compared lingual-alveolar contact pressures during consonant (LACP-Sp) production between adults with and without amyotrophic lateral sclerosis (ALS) over three visits within six months and assessed the relationship between LACP-Sp and speech intelligibility.

METHODS

Ten people with ALS and nine without read sentences with lingual-alveolar consonants embedded as LACP-Sp was recorded. Recordings were done at study entry, then three and six months after entry. Six of ten with ALS had bulbar symptoms detected in clinical encounter at the time of study enrollment (ALS-B); the remaining four had only spinal symptoms (ALS-S).

RESULTS

Main and interaction effects varied across experimental stimuli. However, the pattern of results from the ANOVAs indicated that the ALS-B had lower LACP-Sp values than the other groups. Time main effects were present indicating a reduction in LACP-Sp. However, there were interaction effects for fricatives and/l/, with the ALS-S group demonstrating greater reduction over time than the other groups. Word intelligibility had moderate to large correlations with LACP-Sp but confidence intervals were broad and only a few were statistically significant.

CONCLUSION

LACP-Sp does decrease over time in people with ALS and may reflect a general weakening of the tongue. Confirmation of these group changes will require assessment with a larger sample size.

Lingual-Alveolar Contact Pressure During Speech in Amyotrophic Lateral Sclerosis: Preliminary Findings

PURPOSE

This preliminary study on lingual-alveolar contact pressures (LACP) in people with amyotrophic lateral sclerosis (ALS) had several aims: (a) to evaluate whether the protocol induced fatigue, (b) to compare LACP during speech (LACP-Sp) and during maximum isometric pressing (LACP-Max) in people with ALS (PALS) versus healthy controls, (c) to compare the percentage of LACP-Max utilized during speech (%Max) for PALS versus controls, and (d) to evaluate relationships between LACP-Sp and LACP-Max with word intelligibility.

METHOD

Thirteen PALS and 12 healthy volunteers produced /t, d, s, z, l, n/ sounds while LACP-Sp was recorded. LACP-Max was obtained before and after the speech protocol. Word intelligibility was obtained from auditory-perceptual judgments.

RESULTS

LACP-Max values measured before and after completion of the speech protocol did not differ. LACP-Sp and LACP-Max were statistically lower in the ALS bulbar group compared with controls and PALS with only spinal symptoms. There was no statistical difference between groups for %Max. LACP-Sp and LACP-Max were correlated with word intelligibility.

CONCLUSIONS

It was feasible to obtain LACP-Sp measures without inducing fatigue. Reductions in LACP-Sp and LACP-Max for bulbar speakers might reflect tongue weakness. Although confirmation of results is needed, the data indicate that individuals with high word intelligibility maintained LACP-Sp at or above 2 kPa and LACP-Max at or above 50 kPa.

Bilabial Contact Pressure and Oral Air Pressure during Tracheoesophageal Speech

Objectives:

This study compared bilabial contact pressure (CPsp) and oral air pressure (Po) for /p/, /b/, and /m/ produced by tracheoesophageal (TE) versus laryngeal speakers. Nonspeech maximum bilabial contact pressures (CPmax) were measured to calculate the percentage of the range utilized for bilabial phonemes.

Methods:

Ten TE speakers and 10 laryngeal speakers produced syllables and sentences loaded with bilabial phonemes. The CPsp was measured with a miniature pressure transducer on the lower lip while the Po was simultaneously measured with a catheter in the corner of the mouth coupled to a differential pressure transducer. The speakers completed a non-speech lip-press task with the contact pressure transducer in place.

Results:

The TE speakers produced bilabial phonemes with significantly higher CPsp and Po than did laryngeal speakers. There was no difference in CPmax between the groups. The percentage of the contact pressure range utilized for bilabial phonemes was significantly higher for TE speakers.

Conclusions:

The increased CPsp and Po exhibited by TE speakers may reflect an attempt to overexaggerate articulation, although an alternate explanation related to neoglottal and oral aerodynamics must also be considered in future work. Subsequent studies evaluating the relationships between magnitude of articulatory contact pressure, phoneme intelligibility, and speaker's sense of effort should contribute to a better understanding of TE speech demands and may guide novel interventions to facilitate TE speech intelligibility.

Tongue-palate contact pressure, oral air pressure, and acoustics of clear speech

PURPOSE

The authors compared articulatory contact pressure (ACP), oral air pressure (Po), and speech acoustics for conversational versus clear speech. They also assessed the relationship of these measures to listener perception.

METHOD

Twelve adults with normal speech produced monosyllables in a phrase using conversational and clear speech. Target phonemes were /t, d, s, z, l, n/. ACP was measured at a point of articulatory contact; Po was sensed by a catheter open in the posterior oral cavity.

RESULTS

ACP was increased to a greater extent in clear speech for /t, d, z/. Po was increased to a greater extent for /t, d/. Acoustic changes also occurred in terms of segment durations, speaking rate, and CV dB ratio. Regression analysis indicated that segment duration was the strongest predictor of listener ratings of speech clarity, followed by an index of articulatory effort and speaking rate.

CONCLUSION

Articulatory effort, as indexed by ACP, Po, and CV dB ratio, was increased to varying degrees depending on the consonant. Greatest changes occurred for /t, d/. Durational measures at both the segment and the phrase level were also important for predicting listener ratings of speech clarity.

Perceptual and acoustic evidence of speaker adaptation to a thin pseudopalate

The purpose of this study was to examine the effect of a thin pseudopalate on the speech of normal adults. It was hypothesized that speech would be initially altered, but speakers would adapt quickly to the device. Eleven speakers produced words without the pseudopalate and at six intervals with the appliance in place. Consonant acoustics were changed initially, but returned to baseline within approximately 30 minutes. Perceptually, consonant identification and distortion ratings were unchanged when wearing the pseudopalate. Results suggest an initial alteration to speech detectable acoustically, but rapid adaptation, for most speakers. Investigators using thin pseudopalates must recognize that speech is altered, at least initially, and account for this in their procedures and interpretation of results.

Adaptation to an electropalatograph palate: acoustic, impressionistic, and perceptual data

PURPOSE

The purpose of this study was to evaluate adaptation to the electropalatograph (EPG) from the perspective of consonant acoustics, listener perceptions, and speaker ratings.

METHOD

Seven adults with typical speech wore an EPG and pseudo-EPG palate over 2 days and produced syllables, read a passage, counted, and rated their adaptation to the palate. Consonant acoustics, listener ratings, and speaker ratings were analyzed.

RESULTS

The spectral mean for the burst (/t/) and frication (/s/) was reduced for the first 60-120 min of wearing the pseudo-EPG palate. Temporal features (stop gap, frication, and syllable duration) were unaffected by wearing the pseudo-EPG palate. The EPG palate had a similar effect on consonant acoustics as the pseudo-EPG palate. Expert listener ratings indicated minimal to no change in speech naturalness or distortion from the pseudo-EPG or EPG palate. The sounds [see text] were most likely to be affected. Speaker self-ratings related to oral comfort, speech, tongue movement, appearance, and oral sensation were negatively affected by the presence of the palatal devices.

CONCLUSIONS

Speakers detected a substantial difference when wearing a palatal device, but the effects on speech were minimal based on listener ratings. Spectral features of consonants were initially affected, although adaptation occurred. Wearing an EPG or pseudo-EPG palate for approximately 2 hr results in relatively normal-sounding speech with acoustic features similar to a no-palate condition.

Perceptions of effort during handgrip and tongue elevation in Parkinson's disease

BACKGROUND

Fatigue and the accompanying perception of effort are often heightened in Parkinson's disease.

OBJECTIVES

To compare performance on three sense-of-effort tasks between patients with PD and matched neurologically normal control subjects.

METHODS

Sixteen PD subjects and 16 normal subjects performed three tasks to assess sense of effort: self-ratings of effort using direct-magnitude estimation, generating pressures at various levels of effort, and sustaining a submaximal level of effort. The latter two tasks were done with handgrip and tongue elevation.

RESULTS

Two of the three tasks successfully differentiated the groups. Subjects with PD provided significantly higher ratings of effort for general daily activities and for speech. During the constant-effort task, pressure curves decayed more rapidly for the PD subjects.

CONCLUSIONS

Performance by PD subjects on the constant-effort task resembled that by normal adults who were pre-fatigued in previous experiments. Results support greater than normal sense-of-effort related to fatigue in PD, and provide preliminary validation of a performance-based physiologic task to assess abnormal sense of effort in this population.