Christine Mooshammer

Jaw and order.

It is well-accepted that the jaw plays an active role in influencing vowel height. The general aim of the current study is to further investigate the extent to which the jaw is active in producing consonantal distinctions, with specific focus on coronal consonants. Therefore, tongue tip and jaw positions are compared for the German coronal consonants /s, , t, d, n, l/, that is, consonants having the same active articulators (apical/laminal) but differing in manner of articulation. In order to test the stability of articulatory positions for each of these coronal consonants, a natural perturbation paradigm was introduced by recording two levels of vocal effort: comfortable, and loud without shouting. Tongue and jaw movements of five speakers of German were recorded by means of EMMA during /aCa/ sequences. By analyzing the tongue tip and jaw positions and their spatial variability we found that (1) the jaws contribution to these consonants varies with manner of articulation, and (2) for all coronal consonants the positions are stable across loudness conditions except for those of the nasal. Results are discussed with respect to the tasks of the jaw, and the possible articulatory adjustments that may accompany louder speech.

Acoustic and articulatory manifestations of vowel reduction in German

Recent phonological approaches incorporate phonetic principles in the motivation of phonological regularities, e.g. vowel reduction and neutralization in unstressed position by target undershoot. So far, evidence for this hypothesis is based on impressionistic and acoustic data but not on articulatory data. The major goal of this study is to compare formant spaces and lingual positions during the production of German vowels for combined effects of stress, accent and corrective contrast. In order to identify strategies for vowel reduction independent of speaker-specific vocal-tract anatomies and individual biomechanical properties, an approach similar to the Generalized Procrustes Analysis was applied to formant spaces and lingual vowel target positions. The data basis consists of the German stressed and unstressed full vowels /i …I y …Y e… E E… P… { a… ao …O u …U / from seven speakers recorded by means of electromagnetic midsagittal articulography (EMMA). Speaker normalized articulatory and formant spaces gave evidence for a greater degree of coarticulation with the consonant context for unstressed vowels as compared to stressed vowels. However, only for tense vowels could spatial reduction patterns be attributed to vowel shortening, whereas lax vowels were reduced without shortening. The results are discussedinthelightofcurrent theoriesofvowel reduction, i.e.target undershoot, Adaptive Dispersion Theory and Prominence Alignment.

Articulatory analysis of the German vowel system

It is undoubtedly the case that what, purely for the sake of convenience, we will refer to as the tense-lax opposition has been the most debated feature of the German vowel system, both in the phonetic and phonological literature. We will not attempt to cover this debate here, but for reviews from various points of view see for example, Mooshammer (1998), Becker (1998), Sendlmeier (1985), Ramers (1988), Wood (1975 ab), Fischer-Jørgensen (1985). From the point of view of our principal interest in the kinematics of speech, one of the most intriguing aspects of the debate – more so than the rather static approach of the quantity vs. quality discussion – has come from the long series of phonological papers that capture the distinction in more dynamic terms (as Anders Löfqvist once said, “the movement is the message”), particularly in the link between vowel and following consonant. Thus terms such as syllable-cut ( Silbenschnitt ) arose, with smoothly cut ( sanft geschnittene ) syllables containing tense vowels, and abruptly cut ( scharf geschnittene ) syllables containing lax vowels (cf. Sievers 1901, and especially the more recent formulations of Vennemann 1991, embedding the opposition firmly in a prosodic theory of syllable structure). The corresponding terminology favoured by Trubetzkoy (1939), following the approach of Jespersen (1913), would be loose contact ( loser Anschluss ) for tense vowels, and close contact (fester Anschluss ) for lax vowels. The terms used throughout the 20 th century for this very consistent intuition clearly suggest that characteristic movement differences should be observable, but attempts to find a phonetic substrate were – equally consistently – inconclusive (e.g Fischer-Jørgensen/Jørgensen 1969, but see Spiekermann 2000 and this volume). In this contribution we review the results of articulatory investigations of German vowel production that have been carried out in our laboratories over the last few years. Given that our emphasis is on articulatory analysis we have not attempted to review acoustic analyses of the German vowel system. In addition, while, in the light of the above remarks, the question of the so-called tense-lax opposition will be very much to the fore in this paper, we would like to emphasize that in our opinion it is only possible to understand how the speech motor system copes with the task of realizing such an opposition – i.e what spatial and tem-

Prosodic and segmental effects on EPG contact patterns of word-initial German clusters

This study investigates the effects of segmental composition and prosodic variation, namely boundary strength and lexical stress, on the production of word-initial clusters in German. The internal structure of the clusters /kl, kn, ks, sk/ has been analyzed by means of EPG recordings from seven speakers of German. Derived temporal and spatial parameters indicate that /kn/ is consistently produced with a lag between the consonants and /kl/ with considerable overlap. This categorical difference is also stable across stress and boundary conditions and is attributed to manner-based and perceptual recoverability constraints. No clear pattern emerges for /sk/ and /ks/. Therefore, stability of temporal organization across prosodic conditions is only tested for /kl/ and /kn/. Temporally, boundary level affects the duration of the adjacent consonant and the overlap within the clusters /kn/ and /kl/, whereas spatially /k/ is affected only in /kn/ but not in /kl/. Stress effects are not restricted to the nucleus but also affect the internal organization of the clusters. The interplay between segmental and prosodic timing effects indicates that the internal structure of clusters shows linguistically crucial and highly constrained timing patterns which can only vary within certain limits.

Stress distinction in German: simulating kinematic parameters of tongue-tip gestures

Abstract Levels of stress are not only distinguished by varying fundamental frequency contours but also by changes of supralaryngeal parameters, e.g., unstressed syllables exhibit reduced movement amplitudes and durations compared with stressed syllables. To investigate the effect of deaccentuation on apical gestures in /tVt/ sequences with all vowels of German, we recorded lingual movements of five speakers by means of EMMA. Movement paths of recorded stressed items were manipulated to simulate kinematic parameters of recorded unstressed items in three different ways: truncation, rescaling and combined truncation and rescaling. We assumed that the simulation type that generated parameters most similar to recorded unstressed items can be interpreted in terms of a generalized motor program for deaccentuation. The following parameters of simulated movements were compared with measured unstressed items: movement durations, peak velocities, distances, interval between velocity peaks in percent of syllable duration, symmetry of velocity profiles and number of acceleration peaks between velocity peaks. Combined simulations resembled most closely the kinematic parameters of unstressed items but could not generate the smaller amplitudes of unstressed syllables with lax vowels, since durational reduction of lax vowels due to deaccentuation was very small, i.e., the spatial reduction was not proportional to the temporal reduction for lax items. Therefore, it can be concluded that with the method used here no single parameter or pattern could be found whose manipulation results in the kinematic characteristics of unstressed syllables, which speaks against the concept of a generalized motor program for deaccentuation.

Acoustic and laryngographic measures of the laryngeal reflexes of linguistic prominence and vocal effort in German

This study uses acoustic and physiological measures to compare laryngeal reflexes of global changes in vocal effort to the effects of modulating such aspects of linguistic prominence as sentence accent, induced by focus variation, and word stress. Seven speakers were recorded by using a laryngograph. The laryngographic pulses were preprocessed to normalize time and amplitude. The laryngographic pulse shape was quantified using open and skewness quotients and also by applying a functional version of the principal component analysis. Acoustic measures included the acoustic open quotient and spectral balance in the vowel /e/ during the test syllable. The open quotient and the laryngographic pulse shape indicated a significantly shorter open phase for loud speech than for soft speech. Similar results were found for lexical stress, suggesting that lexical stress and loud speech are produced with a similar voice source mechanism. Stressed syllables were distinguished from unstressed syllables by their open phase and pulse shape, even in the absence of sentence accent. Evidence for laryngeal involvement in signaling focus, independent of fundamental frequency changes, was not as consistent across speakers. Acoustic results on various spectral balance measures were generally much less consistent compared to results from laryngographic data.

Bridging planning and execution: Temporal planning of syllables.

This study compares the time to initiate words with varying syllable structures (V, VC, CV, CVC, CCV, CCVC). In order to test the hypothesis that different syllable structures require different amounts of time to prepare their temporal controls, or plans, two delayed naming experiments were carried out. In the first of these the initiation time was determined from acoustic recordings. The results confirmed the hypothesis but also showed an interaction with the initial segment (i.e., vowel-initial words were initiated later than words beginning with consonants, but this difference was much smaller for words starting stops compared to /l/ or /s/). Adding a coda did not affect the initiation time. In order to rule out effects of segment-specific articulatory to acoustic interval differences, a second experiment was performed in which speech movements of the tongue, the jaw and the lips were recorded by means of electromagnetic articulography. Results from initiation time, based on articulatory measurements, showed a significant syllable structure effect with VC words being initiated significantly later than CV(C) words. Only minor effects of the initial segment were found. These results can be partly explained by the amount of accumulated experience a speaker has in coordinating the relevant gesture combinations and triggering them appropriately in time.

The coarticulation/invariance scale: Mutual information as a measure of coarticulation resistance, motor synergy, and articulatory invariance

Coarticulation and invariance are two topics at the center of theorizing about speech production and speech perception. In this paper, a quantitative scale is proposed that places coarticulation and invariance at the two ends of the scale. This scale is based on physical information flow in the articulatory signal, and uses Information Theory, especially the concept of mutual information, to quantify these central concepts of speech research. Mutual Information measures the amount of physical information shared across phonological units. In the proposed quantitative scale, coarticulation corresponds to greater and invariance to lesser information sharing. The measurement scale is tested by data from three languages: German, Catalan, and English. The relation between the proposed scale and several existing theories of coarticulation is discussed, and implications for existing theories of speech production and perception are presented.

Articulatory coordination in word-initial clusters of German

Abstract Intra-gestural and inter-gestural coordination in German word-initial consonant clusters /kl, kn, ks, pl, ps/ is investigated in four speakers by means of EMA as a function of segmental make-up and prosodic variation, i.e. prosodic boundary strength and lexical stress. Segmental make-up is shown to determine the extent of articulatory overlap of the clusters, with /kl/ exhibiting the highest degree, followed by /pl/, /ps/, /ks/ and finally /kn/. Prosodic variation does not alter this order. However, overlap is shown to be affected by lexical stress in /kl/ and /ps/ and by boundary strength in /pC/ clusters. This indicates that boundary effects on coordination are stronger for clusters with little inter-articulator dependence (e.g. lips + tongue tip in /pl/ vs. tongue back+tongue tip in /kl/). The results also show that the extent to which prosodic factors affect articulation interacts with the position of the affected segment in the sound sequence: In general, boundary strength strongly affects the clusters first consonant while lexical stress influences the second consonant. This indicates that prosodic effects are strongest at their source (i.e. the boundary or the stressed nucleus) and decrease in strength with distance from their source. However, prosodic lengthening effects can reach the more distal consonant in clusters with a high degree of overlap and high inter-articulator dependence. Besides these aspects the discussion covers differences in measures of articulatory coordination.

How to stretch and shrink vowel systems: results from a vowel normalization procedure.

One of the goals of phonetic investigations is to find strategies for vowel production independent of speaker-specific vocal-tract anatomies and individual biomechanical properties. In this study techniques for speaker normalization that are derived from Procrustes methods were applied to acoustic and articulatory data. More precisely, data consist of the first two formants and EMMA fleshpoint markers of stressed and unstressed vowels of German from seven speakers in the consonantal context /t/. Main results indicate that (a) for the articulatory data, the normalization can be related to anatomical properties (palate shapes), (b) the recovery of phonemic identity is of comparable quality for acoustic and articulatory data, (c) the procedure outperforms the Lobanov transform in the acoustic domain in terms of phoneme recovery, and (d) this advantage comes at the cost of partly also changing ellipse orientations, which is in accordance with the formulation of the algorithms.