ZASPiL 42 = Papers in Phonetics and Phonology
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Low- dimensional and speaker-independent linear vocal tract parametrizations can be obtained using the 3-mode PARAFAC factor analysis procedure first introduced by Harshman et al. (1977) and discussed in a series of subsequent papers in the Journal of the Acoustical Society of America (Jackson (1988), Nix et al. (1996), Hoole (1999), Zheng et al. (2003)). Nevertheless, some questions of importance have been left unanswered, e.g. none of the papers using this method has provided a consistent interpretation of the terms usually referred to as "speaker weights". This study attempts an exploration of what influences their reliability as a first step towards their consistent interpretation. With this in mind, we undertook a systematic comparison of the classical PARAFAC1 algorithm with a relaxed version, of it, PARAFAC2. This comparison was carried out on two different corpora acquired by the articulograph, which varied in vowel qualities, consonantal contexts, and the paralinguistic features accent and speech rate. The difference between these statistical approaches can grossly be described as follows: In PARAFAC1, observation units pertain to the same set of variables and the observation units are comparable. In PARAFAC2, observations pertain to the same set of variables, but observation units are not comparable. Such a situation can be easily conceived in a situation such as we are describing: The operationalization we took relies on the comparability of fleshpoint data acquired from different speakers, which need not be a good assumption due to influences like sensor placement and morphological conditions.
In particular, the comparison between the two different approaches is carried out by means of so-called "leverages" on different component matrices originating in regression analysis, calculated as v = diag(A(A A)−1A ) and delivering information on how "influential" a particular loading matrix is for the model. This analysis could potentially be carried out component by component, but we confined ourselves to effects on the global factor structure. For vowels, the most influential loadings are those for the tense cognates of non-palatal vowels. For speakers, the most prominent result is the relative absence of effects of the paralinguistic variables. Results generally indicate that there is quite little influence of the model specification (i.e. PARAFAC1 or PARAFAC2) on vowel and subject components. The patterns for the articulators indicate that there are strong differences between speakers with respect to the most influential measurement as revealed by PARAFAC2: In particular, the most influential y-contribution is the tongue-back for some talkers and the tongue-dorsum for other speakers. With respect to the speaker weights, again, the leverage patterns are very similar for both PARAFAC-versions. These patterns converge with the results of the loading plots, where the articulator profiles seem to be most altered by the use of PARAFAC2. These findings, in general, are interpreted as evidence for the reliability of the PARAFAC1 speaker weights.
Syllable cut is said to be a phonologically distinctive feature in some languages where the difference in vowel quantity is accompanied by a difference in vowel quality like in German. There have been several attempts to find the corresponding phonetic correlates for syllable cut, from which the energy measurements of vowels by Spiekermann (2000) proved appropriate for explaining the difference between long, i.e. smoothly, and short, i.e. abruptly cut, vowels: in smoothly cut vowels, a larger number of peaks was counted in the energy contour which were located further back than in abruptly cut segments, and the overall energy was more constant throughout the entire nucleus. On this basis, we intended to compare German as a syllable cut language and Hungarian where the feature was not expected to be relevant. However, the phonetic correlates of syllable cut found in this study do not entirely confirm Spiekermann's results. It seems that the energy features of vowels are more strongly connected to their duration than to their quality.
This study reports on the results of an airflow experiment that measured the duration of airflow and the amount of air from release of a stop to the beginning of a following vowel in stop vowel-sequences of German. The sequences involved coronal, labial and velar voiced and voiceless stops followed by the vocoids /j, i:, ı, ɛ, ʊ, a/. The experiment tested the influence of the three factors voicing of stop, place of stop articulation, and the following vocoid context on the duration and amount of air as possible explanation for assibilation processes. The results show that the voiceless stops are related to a longer duration and more air in the release phase than voiced ones. For the influence of the vocoids, a significant difference could be established between /j/ and all other vocoids for the duration of the release phase. This difference could not be found for the amount of air over this duration. The place of articulation had only restricted influence. Velars resulted in significantly longer duration of the release phase compared to non-velars. A significant difference in amount of air between the places of articulation could not be found.
The present article is a follow-up study of the investigation of labiodentals in German and Dutch by Hamann & Sennema (2005), where we looked at the perception of the Dutch labiodental three-way contrast by German listeners without any knowledge of Dutch and German learners of Dutch. The results of this previous study suggested that the German voiced labiodental fricative /v/ is perceptually closer to the Dutch approximant /ʋ/ than to the corresponding Dutch voiced labiodental fricative /v/. These perceptual indications are attested by the acoustic findings in the present study. German /v/ has a similar harmonicity median and a similar centre of gravity to Dutch /ʋ/, but differs from Dutch /v/ in these parameters. With respect to the acoustic parameter of duration, German /v/ lies closer to the Dutch /v/ than to the Dutch /ʋ/.
(Non)retroflexivity of slavic affricates and its motivation : Evidence from polish and czech <č>
(2005)
The goal of this paper is two-fold. First, it revises the common assumption that the affricate <č> denotes /t͡ʃ/ for all Slavic languages. On the basis of experimental results it is shown that Slavic <č> stands for two sounds: /t͡ʃ/ as e.g. in Czech and /ʈʂ/ as in Polish.
The second goal of the paper is to show that this difference is not accidental but it is motivated by perceptual relations among sibilants. In Polish, /t͡ʃ/ changed to /ʈʂ/ thus lowering its sibilant tonality and creating a better perceptual distance to /tɕ/, whereas in Czech /t͡ʃ/ did not turn to /ʈʂ/, as the former displayed sufficient perceptual distance to the only affricate present in the inventory, namely, the alveolar /t͡s/. Finally, an analysis of Czech and Polish affricate inventories is offered.
While the perilinguistic child is endowed with predispositions for the categorical perception of phonetic features, their adaptation to the native language results from a long evolution from the end of the first year of age up to the adolescence. This evolution entails both a better discrimination between phonological categories, a concomitant reduction of the discrimination between within-category variants, and a higher precision of perceptual boundaries between categories. The first objective of the present study was to assess the relative importance of these modifications by comparing the perceptual performances of a group of 11 children, aged from 8 to 11 years, with those of their mothers. Our second objective was to explore the functional implications of categorical perception by comparing the performances of a group of 8 deaf children, equipped with a cochlear implant, with normal-hearing chronological age controls. The results showed that the categorical boundary was slightly more precise and that categorical perception was consistently larger in adults vs. normal-hearing children. Those among the deaf children who were able to discriminate minimal distinctions between syllables displayed categorical perception performances equivalent to those of normal-hearing controls. In conclusion, the late effect of age on the categorical perception of speech seems to be anchored in a fairly mature phonological system, as evidenced the fairly high precision of categorical boundaries in pre-adolescents. These late developments have functional implications for speech perception in difficult conditions as suggested by the relationship between categorical perception and speech intelligibility in cochlear implant children.
Articulatory token-to-token variability not only depends on linguistic aspects like the phoneme inventory of a given language but also on speaker specific morphological and motor constraints. As has been noted previously (Perkell (1997), Mooshammer et al. (2004)), speakers with coronally high "domeshaped" palates exhibit more articulatory variability than speakers with coronally low "flat" palates. One explanation for that is based on perception oriented control by the speaker. The influence of articulatory variation on the cross sectional area and consequently on the acoustics should be greater for flat palates than for domeshaped ones. This should force speakers with flat palates to place their tongue very precisely whereas speakers with domeshaped palates might tolerate a greater variability. A second explanation could be a greater amount of lateral linguo-palatal contact for flat palates holding the tongue in position. In this study both hypotheses were tested.
In order to investigate the influence of the palate shape on the variability of the acoustic output a modelling study was carried out. Parallely, an EPG experiment was conducted in order to investigate the relationship between palate shape, articulatory variability and linguo-palatal contact.
Results from the modelling study suggest that the acoustic variability resulting from a certain amount of articulatory variability is higher for flat palates than for domeshaped ones. Results from the EPG experiment with 20 speakers show that (1.) speakers with a flat palate exhibit a very low articulatory variability whereas speakers with a domeshaped palate vary, (2.) there is less articulatory variability if there is lots of linguo-palatal contact and (3.) there is no relationship between the amount of lateral linguo-palatal contact and palate shape. The results suggest that there is a relationship between token-to-token variability and palate shape, however, it is not that the two parameters correlate, but that speakers with a flat palate always have a low variability because of constraints of the variability range of the acoustic output whereas speakers with a domeshaped palate may choose the degree of variability. Since linguo-palatal contact and variability correlate it is assumed that linguo-palatal contact is a means for reducing the articulatory variability.
It is one of the most highly debated issues in loanword phonology whether loanword adaptations are phonologically or phonetically driven. This paper addresses this issue and aims at demonstrating that only the acceptance of both a phonological as well as a phonetic approximation stance can adequately account for the data found in Japanese. This point will be exemplified with the adaptation of German and French mid front rounded vowels in Japanese. It will be argued that the adaptation of German /oe/ and /ø/ as Japanese /e/ is phonologically grounded, whereas the adaptation of French /oe/ and /ø/ as Japanese /u/ is phonetically grounded. This asymmetry in the adaptation process of German and French mid front rounded vowels and further examples of loans in Japanese lead to the only conclusion that both strategies of loanword adaptation occur in languages. It will be shown that not only perception, but also the influence of orthography, of conventions and the knowledge of the source language play a role in the adaptation process.
In order to investigate the articulatory processes of the hasty and mumbled speech of clutterers, the kinematic variability was analysed by means of electromagnetic midsagittal articulography (EMMA). In contrast to stutterers, clutterers improve their intelligibility by concentrating on their speech task. Variability is an important criterion in comparable studies of stuttering and is discussed in terms of the stability of the speech motor system. The aim of the current study was to analyse the spatial and temporal variability in the speech of three clutterers and three control speakers. All speakers were native speakers of German. The speech material consisted of repetitive CV-syllables and foreign words, because clutterers have the most severe problems with long words which have a complex syllable structure. The results showed a higher quotient of variation for clutterers in the foreign word production. For the syllable repetition task, no significant differences between clutterers and controls were found. The extremely large and variable displacements were interpreted as a strategy that helps clutterers to improve the intelligibility of their speech.
Studying kinematic behavior in speech production is an indispensable and fruitful methodology in order to describe for instance phonemic contrasts, allophonic variations, prosodic effects in articulatory movements. More intriguingly, it is also interpreted with respect to its underlying control mechanisms. Several interpretations have been borrowed from motor control studies of arm, eye, and limb movements. They do either explain kinematics with respect to a fine tuned control by the Central Nervous System (CNS) or they take into account a combination of influences arising from motor control strategies at the CNS level and from the complex physical properties of the peripheral speech apparatus. We assume that the latter is more realistic and ecological. The aims of this article are: first, to show, via a literature review related to the so called '1/3 power law' in human arm motor control, that this debate is of first importance in human motor control research in general. Second, to study a number of speech specific examples offering a fruitful framework to address this issue. However, it is also suggested that speech motor control differs from general motor control principles in the sense that it uses specific physical properties such as vocal tract limitations, aerodynamics and biomechanics in order to produce the relevant sounds. Third, experimental and modelling results are described supporting the idea that the three properties are crucial in shaping speech kinematics for selected speech phenomena. Hence, caution should be taken when interpreting kinematic results based on experimental data alone.