Maria-Josep Solé

Aerodynamic characteristics of trills and phonological patterning

Abstract The present study attempts to characterize the aerodynamic conditions required for the production of apical trills and to account for some universal tendencies in the patterning of trills in terms of their aerodynamic and distinctiveness requirements. In order to ascertain the aerodynamic conditions required for trills, oropharyngeal pressure (Po) and airflow were recorded simultaneously in two subjects producing voiced and voiceless trills. The backpressure during trills was intermittently bled with catheters of varying diameter, and thus impedance. It was found that (1) voiceless trills show a higher Po and a larger rate of flow than voiced trills, which generates friction noise across the lingual constriction; (2) voiceless trills are more robust to changing aerodynamic conditions but less distinct auditorily, as inferred from acoustic data; (3) the Po and airflow conditions for voiced trills and fricatives show very similar values, with trills showing a narrower range of allowable variation. The behavior of trills in varying aerodynamic conditions accounts for observed phonological patterns: the universal preference for voiced trills, the alternation between trills and fricatives, trill devoicing, and the lack of nasal trills.

Phonetic and Phonological Processes: The Case of Nasalization:

The aim of this paper is to differentiate between universal phonetic processes and language-specific phonological processes. Cross-linguistic data on coarticulatory nasalization of vowels preceding a nasal consonant were obtained across different speech rates in American English and Spanish. The data show that in American English the temporal extent of vowel nasalization varies with speech rate, whereas in Spanish, nasalization has a constant temporal extent across speech rates. It is argued that the different behavior of nasalization in these two languages reflects different inputs to speech production: In Spanish, vowels followed by a nasal are targeted as oral and nasalization is an unintended vocal tract constraint, whereas, in American English, vowels are targeted as nasalized and vowel nasalization is a phonological effect, intentionally implemented by the speaker. It is suggested that in American English, vowels followed by a tautosyllabic nasal are phonologically specified as nasal as a result of sound change. Data on perceived vowel nasalization in American English are reviewed and shown to be compatible with this proposal.

Spatio-temporal patterns of velopharyngeal action in phonetic and phonological nasalization

The aim of this paper is to differentiate between effects of phonetic implementation and effects of phonological structure in the adjustment of articulatory trajectories to varying speech rate. Cross-linguistic data on coarticulatory nasalization of vowels preceding a nasal consonant at different speech rates were analyzed in American English and Spanish. The two languages show different patterns of timing, magnitude, duration, and velocity of velopharyngeal movements. In Spanish the velocity of velar port (VP) opening and closing gestures is not affected by differences in speech rate, which suggests that these trajectories reflect the default articulatory movements automatically implemented by the phonetic component. In American English, VP closing velocity is not affected by speech rate whereas opening velocity adjusts to variations in speech rate to ensure vowel nasalization across rates. The careful regulation of VP opening velocity suggests that it is centrally controlled. Interarticulatory timing data support this interpretation: In Spanish, vowels are oral for most of their duration; onset of VP opening is timed relative to the following nasal consonant and peak VP size occurs at nasal consonant onset across rates, which suggests that the motor commands for opening the velar port are part of the instructions for the nasal consonant. In American English, on the other hand, VP opening onset coincides with vowel onset and peak VP size occurs in the middle of the vowel across rates, which indicates that opening movements are part of the programming instructions for the vowel. It is argued that, in Spanish, vowels followed by a nasal consonant are targeted as oral and are nasalized as a result of a coarticulatory effect, whereas, in American English, vowels are targeted as nasalized as a result of a phonological rule.

Aerodynamic characteristics of trills

What are the aerodynamic conditions required for trills? To find out we had two subjects produce steady‐state voiced, voiceless, and ejective alveolar trills. The backpressure during trills was intermittently bled with a tube of varying diameter (and thus impedance) inserted in the speaker’s mouth via the buccal sulcus and gap behind the back molars. Intraoral pressure was measured via a catheter inserted into the pharynx through the nose. The variation, impairment, or extinction of trilling as a function of gradual decrease in intraoral pressure was analyzed acoustically. It was found that (1) bleeding the oro‐pharyngeal pressure by 2 cm H2O impaired sustained trilling; (2) the minimum Po required to sustain tongue‐tip vibration is lower than that required to initiate it; (3) extinction (and reinitiation) of trilling generally results in a fricative; (4) the range of Po variation for trills is narrower than that for fricatives; (5) voiceless and ejective trills are significantly less affected by venting ...

Effects of syllable position on sound change: An aerodynamic study of final fricative weakening

Abstract This study explores the differences between the aerodynamic characteristics of onset and coda fricatives. Such differences may account for the weakening of syllable-final fricatives found synchronically and diachronically in a variety of languages. Simultaneous oral pressure, airflow, and audio-signal were obtained for two English speakers. Aerodynamic and acoustic analyses showed that, in comparison with onset fricatives, coda fricatives exhibit (i) a slower oral pressure build-up, (ii) a lower pressure peak, (iii) a delayed onset of audible frication, and (iv) lower intensity of frication. In order to provide high flow for frication, voiceless coda fricatives show earlier glottal opening (i.e., a larger increase in flow at the VC transition) than onset fricatives, suggesting compensatory strategies. The findings suggest that modification of the aerodynamic conditions – velocity and duration of flow through the oral constriction – due to a decreased oral gesture syllable-finally and/or lowered subglottal pressure utterance-finally (and possibly coarticulation with conflicting segments) make audible friction more difficult for speakers to produce and for listeners to detect, leading to final fricative weakening or loss.

More on post-nasal devoicing: The case of Shekgalagari

Abstract Like other languages of the Sotho-Tswana subgroup of Bantu, Shekgalagari exhibits a process of post-nasal devoicing, a phenomenon which has been at the center of the debate on the phonetic grounding of phonology. The existence of post-nasal devoicing has been questioned, and it has been claimed that it is phonetically unnatural. In this paper, we provide instrumental data that post-nasal devoicing actually exists in Shekgalagari and suggest that it is not necessarily phonetically unnatural. Acoustic and laryngographic data indicate that post-nasal devoicing is a categorical process, i.e., devoiced stops do not differ from underlying voiceless stops in any of the durational, voicing and tonal parameters analyzed. Voiced stops differ from devoiced and voiceless stops in all these parameters. Secondly, the results show that in Shekgalagari (as in Tswana) voiceless stops do not have longer voicing into the closure postnasally than postvocally, in contrast with the findings for most languages. These results undercut the claim that the tendency towards postnasal obstruent voicing is present in all languages. We argue that the two patterns, postnasal voicing and devoicing, may not be as antagonistic as has been assumed, and that both may be derived from a common source, variations in the relative timing of the nasal and oral gestures.

Articulatory adjustments in initial voiced stops in Spanish, French and English

Abstract This work reports cross-languages differences in the voicing of utterance-initial voiced stops, and in the use of active maneuvers to achieve closure voicing, using correlated aerodynamic and acoustic data. Oral pressure, oral and nasal flow, and acoustic data were obtained for utterance-initial /b d p t m/ for 10 speakers of Spanish, 6 speakers of French and 5 speakers of English. Voiced stops were first classified as prevoiced or devoiced. Then they were classified by shape of the oral pressure pulse and/or occurrence of nasal flow or oral flow during the stop closure in an attempt to relate aerodynamic data to motor adjustments to facilitate voicing. Such adjustments were found to be related to (i) language-specific differences in the use of glottal vibration as a cue to the voicing-distinction, (ii) place of articulation, and (iii) speaker dependent variation. Voiceless stops showed no such active maneuvers except nasal leak (i.e. nasal closure following oral closure). Comparison of the timing of oral-velic closure in voiced and voiceless stops showed that nasal closure took place later in voiced than in voiceless stops. The longer nasal leak in voiced compared to voiceless stops is argued to be related to voicing initiation and maintenance. Finally, we seek to find acoustic evidence of articulatory adjustments to lower oral pressure for voicing. A correlation is found between oral pressure and voicing amplitude during the stop closure in the three languages: as oral pressure rises, voicing amplitude decreases. Thus the time course of voicing amplitude during the stop closure allows us to infer whether (any) motor adjustments to keep a low oral pressure for voicing are present but not specifically which ones.

Do nasalized fricatives exist

It has been claimed that nasalized fricatives, even sibilant fricatives, exist in some languages. To assess this claim we sought to discover how much velopharyngeal opening can be present before the acoustic and auditory characteristics of fricatives are affected. Two trained phoneticians produced steady‐state voiced and voiceless strong and weak fricatives. The back pressure was intermittently bled with a tube of varying diameter (and thus impedance) inserted into the speaker’s mouth via the buccal sulcus and the gap behind the back molars, simulating nasal leakage. Intraoral pressure (Po) was sampled via a catheter inserted into the pharynx through the nose. The changes in amplitude and quality of frication were analyzed acoustically. We found that (1) a vent area of about 18 mm2 caused auditorily and acoustically noticeable lessening of fricative energy, e.g., sibilants sounded more like nonsibilants, (2) for a given vent aperture, Po was diminished less for voiceless than voiced fricatives (because th...

Dynamic Acoustic Evidence of Nasalization as a Compensatory Mechanism for Voicing in Spanish Apraxic Speech.

This paper is concerned with the phonetic realization of the voicing contrast by two Spanish speakers with surgery-related apraxia of speech and two matched control speakers. Specifically, it examines whether speakers with AOS, widely reported to have a deficit in laryngeal control, use nasal leak as a compensatory mechanism aimed at facilitating the initiation of voicing in word-initial stops. The results show that the two apraxic speakers produced prevoicing in /b d g/ in only one third of the cases (correctly identified as ‘voiced’). In these cases, however, they exhibited significantly longer prevoicing than control subjects, and this longer voiced portion was closely related to a longer nasal murmur. These results shed light on the compensation strategies used by apraxic subjects to achieve voicing. Differences in the intensity patterns of nasal and voiced stops indicate that apraxic speakers control the timing of velopharyngeal gesture, suggesting that apraxia is a selective impairment.