Acoustic characteristics of speech produced without oral sensation

The Feel of Speech: Multisystem and Polymodal Somatosensation in Speech Production

PURPOSE

The oral structures such as the tongue and lips have remarkable somatosensory capacities, but understanding the roles of somatosensation in speech production requires a more comprehensive knowledge of somatosensation in the speech production system in its entirety, including the respiratory, laryngeal, and supralaryngeal subsystems. This review was conducted to summarize the system-wide somatosensory information available for speech production.

METHOD

The search was conducted with PubMed/Medline and Google Scholar for articles published until November 2023. Numerous search terms were used in conducting the review, which covered the topics of psychophysics, basic and clinical behavioral research, neuroanatomy, and neuroscience.

RESULTS AND CONCLUSIONS

The current understanding of speech somatosensation rests primarily on the two pillars of psychophysics and neuroscience. The confluence of polymodal afferent streams supports the development, maintenance, and refinement of speech production. Receptors are both canonical and noncanonical, with the latter occurring especially in the muscles innervated by the facial nerve. Somatosensory representation in the cortex is disproportionately large and provides for sensory interactions. Speech somatosensory function is robust over the lifespan, with possible declines in advanced aging. The understanding of somatosensation in speech disorders is largely disconnected from research and theory on speech production. A speech somatoscape is proposed as the generalized, system-wide sensation of speech production, with implications for speech development, speech motor control, and speech disorders.

Proprioceptive Acuity Influences Speech Motor Control in Healthy Adult Talkers

PURPOSE

Somatosensory feedback, including proprioception, is important for speech production. This study evaluates proprioceptive acuity of the tongue using a position-matching task and determining if proprioceptive acuity impacts speech motor control in healthy adult talkers.

METHOD

Twenty-five young adults with no history of speech, language, or hearing disorders had their tongue movements recorded with an electromagnetic articulograph while completing a position-matching task. Participants were also asked to repeat two sentences that differed in the somatosensory feedback obtained. One sentence provided both tactile and proprioceptive feedback, whereas the other primarily provided proprioceptive feedback.

RESULTS

Participants ranged in proprioceptive acuity as measured by the position-matching task. Talkers with smaller position-matching errors and, therefore, higher proprioceptive acuity had smaller movements and slower speeds for both sentences. Talkers with lower proprioceptive acuity had reduced speech movement stability for the sentence that primarily provides proprioceptive feedback.

CONCLUSION

Proprioceptive acuity of the tongue can be evaluated using a position-matching task, and acuity is associated with more efficient speech movements and greater speech movement stability, particularly when producing utterances that provide less tactile feedback.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.24293740.

Effects of transitory lingual nerve impairment on speech: an acoustic study of vowel sounds

PURPOSE

The purpose of the study was to evaluate the effects of the lingual nerve impairment on phonetic quality of speech by analyzing the main acoustic features of vowel sounds when the normal lingual nerve function was partly distorted by local anesthesia.

PATIENTS AND METHODS

The study group consisted of 7 men, whose right side lingual nerve was anesthetized with 0.8 mL of Ultracaine D-Suprarenin (Aventis Pharma Deutschland GmpH, Frankfurt am Main, Germany). The speech material analyzed consisted of 8 vowels produced in sentence context by speakers. Every utterance was repeated 10 times with and without local anesthesia. After recording, the speech samples were analyzed with a computerized speech laboratory. In addition, the vowels of 1 man with permanent nerve impairment were studied.

RESULTS

The results show that the deprived function of the tongue after lingual nerve impairment had various effects on vowel quality for every subject. The main acoustic determinants of different vowels, the lowest vocal tract resonances, changed in frequency. In addition, the total duration of vowels changed and the vowels had different fundamental frequencies. However, these effects were extremely individual and variable.

CONCLUSIONS

According to the results of acoustic analysis, the distortion of lingual nerve function has effects on vowel production. Some of these changes were so extensive that they also could be perceptually detectable. Lingual nerve impairment seems to have potential to change speech production.

Cutaneous oral-motor reflexes of children with normal and disordered speech

Cutaneous reflex responses in the human jaw-closing system to low-threshold, mechanical stimulation were investigated in 30 four- to six-year-old children with normal speech and in seven children with disordered speech. Responses of these children were smaller and less frequently observed than those of a seven- to eight-year-old group in an earlier study, suggesting that cutaneous oral-motor reflexes may develop with the acquisition of speech motor skills. Preliminary observations in a very small sample of speech-impaired children suggest that future work should explore the hypothesis that development of cutaneous oral reflexes is delayed in this group. The results of this and other studies suggest that human oral-motor reflexes undergo a pattern of continuous change throughout the lifespan.

Interaction between auditory and oral sensory feedback in speech regulation

To investigate the interaction between the auditory and oral sensory feedback modalities during speech production lingual vibrotactile thresholds were obtained from subjects in the following conditions: (1) before and after speech production with normal auditory feedback, (2) before and after speech production under exposure to auditory masking, and (3) before and after exposure to auditory masking without performing speech tasks. In addition duration measurements were obtained for selected speech sounds to investigate temporal changes in the articulatory patterns of subjects in the various conditions. Lingual sensory decreases and temporal reorganization were observed only in subjects speaking under auditory masking. These data suggest a balanced interaction between auditory and oral sensory feedback modalities which, when disturbed, results in non-phonemic change in speech production.