[Volumetry of the human tongue by MRI]

Mumbling: Macho or Morphology?

PURPOSE

Mumbling as opposed to clear speech is a typical male characteristic in speech and can be the consequence of a small jaw opening. Whereas behavioral reasons have often been offered to explain sex-specific differences with respect to clear speech, the purpose of this study is to investigate a potential anatomical reason for smaller jaw openings in male than in female speakers.

METHOD

Articulatory data from 2 data sets (American English and German) were analyzed with respect to jaw opening in low vowels during speech. Particular focus was placed on sex-specific differences, also incorporating potential interactions with different accent conditions in 1 of the data sets. In addition, a modeling study compared the articulatory consequences of similar jaw-opening settings in a typical male and a typical female articulatory model.

RESULTS

Greater jaw openings were found for the female speakers, in particular in the accented condition, where jaw opening was found to be larger. In line with this finding, the modeling study showed that similar jaw-opening settings in male and female speakers led to differences in pharyngeal constriction, resulting in complete radico-pharyngeal closure in the male model.

CONCLUSION

The empirical and modeling findings suggest a possible physiological component in sex-specific differences in speech clarity for low vowels.

Mood-induced variations of mandible and tongue postures

Twelve young adults in a good general health were observed during habitual posture of tongue and jaw in different emotional conditions induced by watching three video sequences. The position of the mandible was tracked by the displacements of an electromagnetic sensor glued to the chin. The tongue-to-palate distance was obtained by 2-D location of three electromagnetic sensors placed on the tongue upper midline surface. Head displacements were evaluated with a sensor fixed to an upper central incisor and were subtracted from corresponding displacements of tongue and chin sensors to obtain the real tongue and mandible positions during continuous recording sequences. Emotional conditioning by a fear movie influenced the vertical position of the mandible: the mean interarch distances during the fear movie (2·34 ± 0·24 mm) were significantly different from those measured during the tender (3·13 ± 0·35) and neutral (3·42 ± 0·80) movies, respectively (anova repeated measure, SNK; P < 0·05). anova repeated measure indicated that the tongue-to-palate distance differed significantly when the subjects were watching the conditioning movies (P = 0·003), the tip of the tongue taking a lower position during the fear movie than during the tender and neutral movies.

Contributory role of the tongue and mandible in modulating the in-mouth air cavity at rest

OBJECTIVES

The tongue-to-palate distance influences the volume of the in-mouth air cavity (IMAC), thus conditioning the entry of aromatic compounds to the olfactory mucosa site. This study was set out to record the IMAC volume by measuring tongue-to-palate distance at rest.

MATERIALS AND METHODS

Twelve young adults in good general health were tested--lips contacting, with at-rest posture of the tongue and jaw during a silent reading task. Observations in this study were limited to pre- and post-swallowing sequences. The tongue-to-palate distance was measured using three electromagnetic sensors placed on the tongue upper surface. IMAC volume was evaluated from a geometrical model, taking into account the tongue-to-palate distance, the IMAC transversal distance measured from dental casts and historic data giving the anterior-posterior distance of the oral cavity.

RESULTS

(1) In the at-rest posture, the tongue-to-palate distance was significantly greater at the posterior sensor level. (2) A vertical shift in tongue posture at rest frequently appeared following deglutition. The upward shifts were of larger amplitude and more frequent than the downward shifts. (3) Evaluation of the IMAC volume gave an approximate value of 12 ml at rest. (4) The chin sensor at rest was 2.8 ± 0.8 mm below its position when in occlusion.

CONCLUSION

The tongue and mandible contribute to shaping the IMAC volume.

CLINICAL RELEVANCE

These and other results suggest that deglutition changes tongue-to-palate distance and influences aroma release during mastication/deglutition acts through modulation of the IMAC volume.