Electromagnetic Articulometer Research Articles

An electromagnetic articulometer study of tongue and lip troughs

Troughs, which are a discontinuity in anticipatory coarticulation (Perkell 1968), have been shown to occur in the tongue body in /ipi/ and lips in /usu/. An electromagnetic articulometer (EMA) study of a single subject reported previously showed that intraoral pressure during the consonant could not be solely responsible for the downwards tongue body movement observed during the labial consonants (/p, b, m, f, v/); results supported the hypothesis of a secondary tongue gesture during the consonant. Lip troughs during /s/ in rounded contexts were more ambiguous, possibly because of inconsistencies in corpus design. Six new subjects have been recorded using a WAVE EMA system and a revised corpus. Tongue trough magnitudes decreased in the order /f, v/ > /p, b/ > /m/, serving to disprove the aerodynamic hypothesis; they were deeper for long than short consonants (e.g., [iffi] > [ifi]), and converged to the same point in asymmetric vowel contexts. The same type of convergence during the consonant was observed ...

Mind the gap: Electromagnetic articulometer observation of speech articulation in conversational turn-taking

Joe Perkell pioneered the use of electromagnetic articulometry (EMA) for the observation and quantification of the kinematics of speech articulator movements. In the spirit of his research, we have extended these methods to EMA observation of two facing speakers interacting in conversation. The gaps or pauses between turns in speaking are known from acoustic measurement to be relatively short in duration, about 200 ms or the length of a syllable on average, and this gap duration has been shown to be consistent across widely diverse languages and cultures (Stivers et al., 2009). However, because the cognitive latencies for producing a response are much longer than this interval its planning must occur during the incoming turn. Here we provide evidence for this planning from articulator movements that anticipate speech. Movements of sensors attached to the tongue, jaw and lips have been tracked for each of 12 speaker pairs. Gaps are measured as the difference between the acoustic end of one speaker's turn t...

Dual electromagnetic articulometer observation of head movements coordinated with articulatory gestures for interacting talkers in synchronized speech tasks

Previous research has demonstrated that speakers readily entrain to one another in synchronized speech tasks (e.g., Cummins 2002, Vatikiotis-Bateson et al. 2014, Natif et al. 2014), but the mixture of auditory and visual cues they use to achieve such alignment remains unclear. In this work, we extend the dual-EMA paradigm of Tiede et al. (2012) to observe the speech and coordinated head movements of speaker pairs interacting face-to-face during synchronized production in three experimental tasks: the “Grandfather” passage, repetition of short rhythmically consistent sentences, and competing alternating word pairs (e.g., “topper-cop” vs. “copper-top"). The first task was read with no eye contact, the second was read and then produced with eye contact, and the third required continuous eye contact. Head movement was characterized using the tracked position of the upper incisor reference sensor. Prosodic prominence was identified using F0 and amplitude contours from the acoustics, and gestural stiffness on articulator trajectories. Preliminary results show that frequency and amplitude of synchronized head movement increased with task eye contact, and that this was coordinated systematically with both acoustic and articulatory prosodic prominence. [Work supported by NIH.]

Secondary gestures for consonants: An electromagnetic articulometer study of troughs

Troughs, defined as a discontinuity in anticipatory coarticulation (Perkell 1968), have been shown to occur in the tongue body (TB) in /ipi/ and lips in /usu/. In V1CV1 contexts articulators retract from their vowel target during C when not active during C. We investigate the trough phenomenon by testing three hypotheses: (1) high intraoral air pressure during the consonant pushes TB down; (2) absence of vowel articulator activation during C in VCV causes TB to move to the neutral position; (3) the trough is a gesture in itself. Electromagnetic articulometer (EMA) data of the tongue, lips, and jaw were tracked for a trained phonetician producing non-words and real words, varying vowel context and the place, manner, and consonant length. For H1, /iCi/ productions with C={/p,f,m/} and three C durations were studied. For H2, /h/ and /ʔ/ in /iCi/ were examined. Troughs were found in all the labials but not in /h, ʔ/, disproving hypothesis 2; trough magnitude decreased in the order: /f/ > /p/ > /m/, disproving hypothesis 1. Trough magnitude increased with C duration, consistent with H3. Results from asymmetric vowel contexts also support H3, and will be discussed within the context of Articulatory Phonology. [Work supported by NIH.]

The scope of boundary lengthening as a function of lexical stress and pitch accent

Although the phenomenon of boundary lengthening is well established, the scope of the effect and its interaction with prominence is not well understood. It is known that phrase-final prominence is a determining factor. However, it is unclear whether it is lexical stress or pitch accent that drives the effect, and whether the affected domain is continuous or discontinuous. An electromagnetic articulometer (EMA) study of five speakers of Greek was conducted to examine the effect of (1) boundary (word and IP), (2) stress (ultima, penult, or antepenult), and (3) prominence (accented and de-accented) on the duration of phrase-final word articulatory events. In both accented and de-accented conditions, lengthening affected events that immediately preceded the boundary in stress-final words, but was initiated earlier in words with non-final stress. The affected domain was continuous. The stress effect could also be observed in pausing behavior: pauses following phrase-final words were realized with specific vocal tract configurations, and the articulatory movements forming them were longer when stress was final than when non-final. Based on these results, a theoretical account of boundaries is proposed within the Articulatory Phonology framework, with implications for a cross-linguistic model of prosody. [Work supported by NIH.]

Temporal alignment between head gesture and prosodic prominence in naturally occurring conversation: An electromagnetic articulometry study

Studies of the relationship between speech events and gesticulation have suggested that the peak of the prosodic pitch accent serves as a target with which body gestures may be coordinated (Roth, 2002; Loehr, 2004). While previous work has relied on controlled speech elicitation generally restricted to nonrepresentational extension/retraction (Leonard and Cummins, 2011) or iconic (Kelly et al., 2008) gestures, here we examine the kinematics of the speech articulators and associated head movements from pairs of individuals engaged in spontaneous conversation. Age and gender matched native speakers of American English seated 2 m apart were recorded using two electromagnetic articulometer (EMA) devices (Tiede and Mooshammer, 2013). Head movements were characterized by the centroid of reference sensors placed on the left and right mastoid processes and the upper incisors. Pitch accents were coded following the ToBI implementation of Pierrehumbert's intonational framework following Beckman and Elam (1997). Preliminary findings show that the apex (point of maximum excursion) of head movements within an IP in general precedes the peak of the associated pitch accent, and is consistently aligned with co-occurring articulatory events within the syllable. [Work supported by NIH NIDCD-DC-012350.]

Evidence for an articulatory component of phonetic convergence from dual electromagnetic articulometer observation of interacting talkers

Speech audio and articulatory movements of age- and gender-matched speaker pairs have been recorded in face-to-face interaction using two electromagnetic articulometer (EMA) systems simultaneously. Speakers matched for language (AE:AE) were compared with mixed language backgrounds (AE:Spanish, AE:German). Tasks included synchronized, imitated, and spontaneous speech interspersed with repeated baseline utterances for evaluation of mutual accommodation. Euclidean distances (EDs) between vowel midpoint formant frequencies from the initial and final baseline tasks showed symmetric reductions associated with convergence which were larger for the speakers with the same language background. To test whether the observed reduction might be due to fatigue or repetition effects EDs were also calculated between AE speakers who did not participate in the same experiment. Because reduction was minimal for this comparison the possibility that convergence can be attributed to simple optimization is excluded. Kinematic and dynamic convergence was examined on coda velar gestures from the baseline tasks. EDs in peak velocity, sensor path distance, gesture amplitude, and stiffness computed between speakers all showed decreases consistent with convergence. Associated within-speaker differences showed that accommodation was effectively symmetric, and because the speakers moved towards one another the difference was not due to practice or fatigue effects. [Work supported by NIH.]

Effect of syllable onset, coda, and nucleus on degree of skin stretching over the mandible

Movements of the mandible have been shown to correlate with English speech rhythm, and significant differences have been found between native speakers’ mandible movements and those of second-language speakers. A simple, inexpensive method of inferring movements of the mandible is to use video tracking of a chin marker during speech. However, since the skin is free to stretch over the mandible, inferences using the chin marker may not always be accurate. This study examines the degree of skin stretching during onset stop consonant, coda stop consonant, and vowel in CVC syllables spoken as the middle word in a 3-word utterance. We made electromagnetic articulometer (EMA) recordings of two North American English speakers (1 male, 1 female). Measurements were made from coils placed on the lower incisor (LI) and on the skin of the mental protruberance (chin). Preliminary results show that both speakers have significant differences during the syllable nucleus between the LI and chin coils due to onset consonant, but not coda consonant. These results need to be taken into account as we continue to develop a method for video recording jaw displacement patterns in running speech.

Speech articulator movements recorded from facing talkers using two electromagnetic articulometer systems simultaneously.

Two 3-D electromagnetic articulometer systems, the Carstens AG500 and Northern Digital WAVE, have been used simultaneously without mutual interference to record the speech articulator movements of two talkers facing one another 2 m apart. A series of benchmark tests evaluating the stability of fixed distances between sensors attached to a rotating rigid body was first conducted to determine whether the two systems could operate independently, with results showing no significant effect of dual operation on either system. In the experiment proper, two native speakers of American English participated as subjects. Sensors were glued to three points on the tongue, the upper and lower incisors, lips, and left and right mastoid processes for each subject. Independent audio tracks were recorded using separate directional microphones, which were used to align the kinematic data from both subjects during post-processing. Data collected were of two types: extended spontaneous conversation and repeated incongruent word sequences (e.g., talker one produced “cop top...;” talker two “top cop...”). Both talkers show strong positive correlations between speech rate (in syllables/s) and head movement. The word sequences also show error and rate effects related to mutual entrainment. [Work supported by ARC Human Communication Science Network (RN0460284), MARCS Auditory Laboratories, NIH.]

Calibration methods of voltage-to-distance function for an electromagnetic articulometer (EMA) system

In electromagnetic articulometer (EMA) systems, the relationship between the voltage of the received signal and the distance between the transmitter and receiver coils is represented by a voltage-to-distance (VD) function. This paper describes an adaptive calibration method for determining unknown parameters in the VD function in which the parameters are determined using automatically selected local calibration data. This method is compared with the conventional fixed method in which the parameters are computed from calibration data covering the entire measurement area. Experimental results show that the measurement error of the adaptive method is 0.106 mm for a 14×14-cm measurement area and is less than half of that in the fixed method. In addition, this error is the same as that when the region of the receiver position is restricted to a 4×4-cm local area in the fixed method.