When using ultrasound imaging of the tongue for speech recording/research, submental transducer stabilization is required to prevent the ultrasound transducer from translating or rotating in relation ...to the tongue. An iterative prototype of a lightweight three-dimensional-printable wearable ultrasound transducer stabilization system that allows flexible jaw motion and free head movement is presented. The system is completely non-metallic, eliminating interference with co-recorded signals, thus permitting co-collection and co-registration with articulometry systems. A motion study of the final version demonstrates that transducer rotation is limited to 1.25° and translation to 2.5 mm-well within accepted tolerances.
There is increasing evidence that fine articulatory adjustments are made by speakers to reinforce and sometimes counteract the acoustic consequences of nasality. However, it is difficult to attribute ...the acoustic changes in nasal vowel spectra to either oral cavity configuration or to velopharyngeal opening (VPO). This paper takes the position that it is possible to disambiguate the effects of VPO and oropharyngeal configuration on the acoustic output of the vocal tract by studying the position and movement of the tongue and lips during the production of oral and nasal vowels. This paper uses simultaneously collected articulatory, acoustic, and nasal airflow data during the production of all oral and phonemically nasal vowels in Hindi (four speakers) to understand the consequences of the movements of oral articulators on the spectra of nasal vowels. For Hindi nasal vowels, the tongue body is generally lowered for back vowels, fronted for low vowels, and raised for front vowels (with respect to their oral congeners). These movements are generally supported by accompanying changes in the vowel spectra. In Hindi, the lowering of back nasal vowels may have originally served to enhance the acoustic salience of nasality, but has since engendered a nasal vowel chain shift.
It is well known that, for nasal vowels, traditional estimation of the shape of the vocal tract via inference from acoustic characteristics is complicated by the acoustic effects of velopharyngeal ...coupling (i.e. nasalization). Given this complexity, measuring the shape of the vocal tract directly is, perhaps, a more desirable method of assessing oro-pharyngeal configuration. Real-time MRI (rt-MRI) allows us to explore the shape of the entire vocal tract during the production of nasal vowels. This permits us to better assess the contribution of the oro-pharyngeal acoustic transfer function to the acoustic signal, which is otherwise obscured by the conflation of the independent oro-pharyngeal and nasal acoustic transfer functions. The oro-pharyngeal shape associated with nasal vowels has implications for both synchronic and diachronic phonology, particularly in French, where descriptions of nasal vowels have long suggested that differences in oral articulation, in addition to velopharyngeal coupling, serve to distinguish oral and nasal vowels. In this study, we use single-slice rt-MRI (midsagittal slice) and multi-slice rt-MRI (oral, velopharyngeal, mediopharyngeal, and lower pharyngeal slices) to examine three nasal vowels /ɛ˜, ɑ˜, ɔ˜/ and their traditional oral counterparts /ɛ, a, o/ as produced by three female speakers of Northern Metropolitan French (NMF). We find evidence of lingual and pharyngeal articulatory configurations which may, in some cases, enhance formant-frequency-related acoustic effects associated with nasalization, viz., modulation of F1 and F2. Given these findings, we speculate that the synchronic oral articulation of NMF nasal vowels may have arisen—at least in part—due to misperception of the articulatory source of changes in F1 and F2, rather than to mere chance, as has been argued.
•We analyze rt-MRI data from oral/nasal vowels produced by three French speakers.•Measures include vocal tract area estimates and PC analyses of pixel intensities.•Some oral articulations of the nasal vowels enhance nasalization's acoustic effects.•Evidence of enhancement observed for both lingual and pharyngeal articulation.•Synchronic articulation likely resulted from diachronic change due to misperception.
In acoustic studies of vowel nasalization, it is sometimes assumed that the primary articulatory difference between an oral vowel and a nasal vowel is the coupling of the nasal cavity to the rest of ...the vocal tract. Acoustic modulations observed in nasal vowels are customarily attributed to the presence of additional poles affiliated with the naso-pharyngeal tract and zeros affiliated with the nasal cavity. We test the hypothesis that oral configuration may also change during nasalized vowels, either enhancing or compensating for the acoustic modulations associated with nasality. We analyze tongue position, nasal airflow, and acoustic data to determine whether American English /i/ and /a/ manifest different oral configurations when they are nasalized, i.e. when they are followed by nasal consonants. We find that tongue position is higher during nasalized ĩ than it is during oral i but do not find any effect for nasalized ã. We argue that speakers of American English raise the tongue body during nasalized ĩ in order to counteract the perceived F1-raising (centralization) associated with high vowel nasalization.
► Many analyses presuppose that nasal and oral vowels have the same oral properties. ► F1-modulation can be attributed to both nasalization and tongue height. ► We find that the tongue is higher in American English /i/ when preceded by a nasal. ► Speakers may be compensating for F1-modulation associated with nasality. ► Speakers may be resisting phonological vowel nasalization by raising the tongue.
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