Objective: Congenital aglossia is a rare syndrome of born without a tongue. This paper examines  articulatory movements of a congenital aglossic speaker to understand  physiology by which a person, born without a tongue and with no surgical, medical or therapeutic assistance can produce intelligible speech

Background: Aperson with isolated congenital aglossia (PWCA) with intelligible speech was examined using real-time Magnetic Resonance Imaging (rtMRI) to determine vocal-tract shapes during speech production and compare with a person without congenital aglossia (PwoCA).

The PwCA was a 45-year-old female presenting with micrognathia and microsomia with a severe Class II malocclusion. She is the 11th case reported in the literature since 1718.

Methods: Speech stimuli was multiple phoneme combinations, words, phrases and sentences read by  PwCA. Data  acquired using  rtMRI protocol developed specifically for dynamic study of upper airway movements . Previously recorded data from  PwoCA, were used for comparison purposes.

Results: Partial results;

Aglossic speaker forms  lip closure for producing /t/, /d/ in  VCV sequence,  dissimilar to normal

-Articulatory difference between /t/ and /p/ was constriction for /t/ extended  significantly more towards posterior end of vocal-tract making back cavity shorter compared to /p/

-It is known that for transient and frication sources during release of  plosive,  transfer function is dominated by cavity anterior to constriction

-Similarity in anterior cavities for aglossic speaker’s /t/ and /p/ may explain similarity of the F2 loci at release

Conclusions:  

-An important difference between aglossic speaker’s /t/ and /p/ is closure loci and duration

-Articulatory-acoustic modeling studies of plosive consonants have focused primarily at release

therefore one plausible explanation of our findings is that loci at closure are associated to size of back cavity, and loci at release are associated to front cavity, however supporting such a hypothesis would need more data and models.

Results are highly applicable to rehabilitation of oral motor/structural disorders to assist in compensatory speech placements

References: Toutios, A., & Narayanan, S. (2016). Advances in real-time magnetic resonance imaging of the vocal tract for speech science and technology research. APSIPA Transactions on Signal and Information Processing, 5, e6.  

Vaz, C., Ramanarayanan, V., & Narayanan, S. (2013). A two-step technique for MRI audio enhancement using dictionary learning and wavelet packet analysis. In INTERSPEECH-2013, 1312-1315.

« Back to 2017 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/case-study-real-time-mri-articulatory-comparison-of-a-congenital-aglossic-and-normal-speaker/