Michiko Hashi

Differences among speakers in lingual articulation for American English /ɹ/

Abstract X-ray microbeam fleshpoint measures of lingual articulation for pre-vocalic /ɹ/ were obtained for five test words spoken by 53 normal, young adult talkers of American English. The data were used to develop quantitative descriptions of cross-speaker variation in tongue shapes at acoustically-defined r-moments in the test words, and to understand whether and how /ɹ/-related tongue shapes might vary across the available sample of phonetic contexts. Key results suggest that tongue shapes for this sound vary widely across speakers within any single phonetic context, and more continuously than categorically across the representational space. Shapes also vary by context in ways that are similar across most speakers, and in some contexts, in ways that can be expected given simple assumptions about lingual movements associated with adjacent sounds. Interestingly, tongue shapes for American English /ɹ/ do not seem to be reliably linked to gender, measures of oral cavity size, or formant frequencies measured for two of the test words. Together, these results provide unique insight about the nature and bases of inter-speaker variation in lingual articulation for this infamously variable sound, and may prove useful to other investigators interested in speech motor control, speech synthesis, and automatic speech recognition.

Time-varying acoustic and articulatory characteristics of American English [ɹ]: a cross-speaker study

Abstract The present study is an attempt to discover time-varying acoustic correlates of articulatory movements of American English [ɹ] using the X-ray microbeam speech production database. American English [ɹ] is known to be variable in its articulatory postures, whereas a single acoustic correlate—a low third formant—is associated with the sound. A previous study (Westbury, Hashi, & Lindstrom (1998), Speech Communication 26, 203–226) found no relation between articulatory postures and formant frequencies at phonation onset of words beginning with the sound. The present study examined acoustic–articulatory relations in time-varying acoustic and articulatory characteristics in the transition from [ɹ] to a following low- or mid-back vowel. In intervals involving a major F3 rise, a relatively strong correlation (r⩾0.7) was observed between the average rate of change in F3 (F3 slope) and the speed of the tongue pellet closest to the palate at the onset of the major F3 rise. Results from the study are discussed with respect to the acoustic theory of speech production.

Articulatory and acoustic variability of vowels in Japanese and English

Measures of formant frequencies and x‐ray microbeam representations of partial mid‐sagittal tongue contours were made at discrete moments in time for single tokens of each of five brief isolated vowels /i e a o u/ produced by seven native adult speakers of Japanese, and ten comparable speakers of American English. The broad purposes of these measurements were twofold: (1) to increase basic understanding of the relationship between articulatory postures and their acoustic correlates during production of isolated vowels; and (2) to develop preliminary estimates of the extent of articulatory and acoustical variability in vowel production in the two languages. The analysis of patterns among lingual contours achieved by different speakers raises problems regarding normalized description of vowel gestures. Methodological approaches to these problems, and their effects on descriptive summaries of the data, will be discussed. [Work supported by ATR Inf. Proc. Res. Labs. and NIH Grant No. DC00820.]

Relating formants and articulation in intelligibility test words

The study represents an attempt to describe the relationships between formant histories and lingual fleshpoint movements for selected words spoken by five normal, young-adult speakers of American English. The data are drawn from the X-ray Microbeam (XRMB) Speech Production Database. A major purpose of the study is to examine the appropriateness of simple acoustic-to-articulatory inferences that are common in speech research.

Replacement of sensor cables for reducing effects on articulation in the Northern Digital Incorporated's Wave electromagnetic articulography system

This study attempted to improve the five-degrees-of-freedom sensors of the Northern Digital Incorporateds Wave electromagnetic articulography system by replacing their cables with thinner and more flexible cables to reduce interference in articulation. Measurement errors and data loss rates were compared between the original and the proposed sensors. The proposed sensors showed twofold tracking accuracy and data loss rates compared to the original sensors in an experiment using a crank-rocker mechanism. Data loss rates of the proposed sensors increased in articulatory data collection from four speakers. The proposed sensors have been made available commercially.

Improvement of sensor for electromagnetic articulograpy to reduce detrimental effects of sensor attachment on articulation

Electromagnetic articulography (EMA) tracks the position and direction of small wired sensors attached inside and outside of the mouth during articulation. In this study, we improved a five degree-of-freedom sensor of the NDI Wave speech research system, which is a type of EMA system, to reduce the effects of sensor cable on articulation. This was done because the thickness and stiffness of the original cable appeared to interfere with natural articulation. The new cable has the diameter of 0.1 mm, which is thinner than the original, and is more flexible. The degree of interference due to sensor attachment to the articulators was evaluated by comparing the extent of distortion of speech produced by four elderly speakers with new and original sensor attached to their articulators. The speakers produced a Japanese vowel sequence and VCV sequences with the two types of sensors attached to their articulators, and three Japanese speech language pathologists evaluated their speech for the degree of speech disto...

Articulatory timing in sentence production in young normal speakers and speakers with apraxia of speech: A speed history analysis.

Apraxia of speech (AOS) is typically considered as characterized by kinematic timing problems among articulators; however, kinematic descriptions of such phenomenon are scarce. The study describes kinematic timing based on a speed history of the lower lip and the jaw, across speaking rates in young normal speakers and speakers with AOS. Kinematic data were acquired through the x‐ray microbeam system, and data of young normal speakers were taken from the x‐ray microbeam speech production database. A short sentence was the speech material/target. Acoustic correlates of major speed peaks of the jaw and the lower lip, as well as their temporal relationships with each other, were investigated. Of particular interest was how changes in speech rate affect such temporal relationships in normal speakers and speakers with AOS. The goal of this study was to establish a description method of inter‐ and intra‐articulator timing for use in analyses of point‐parametrized articulatory data in sentence‐level materials.

Interarticulator timing in a sentence production in young normal speakers and speakers with apraxia of speech.

Apraxia of speech (AOS) is typically considered as characterized by kinematic timing problems among articulators; however, kinematic descriptions of such phenomenon are scarce. The goal of this study was to describe articulatory timing between the lips and jaw and the lips and tongue in young normal and AOS speakers across three speaking rates, using x‐ray microbeam data. Data of young normal speakers were taken from the x‐ray microbeam speech production database. Lip protrusion and tongue elevation timings were derived from the kinematic and acoustic data in the production of “too” in the sentence “The other one is too big” and lip and jaw closing timings for /b/ and /w/ were derived from the kinematic data of the same sentence. The temporal relationships between these articulatory movements in each event were then examined with consideration of the effect of speaking rate. The results are discussed in relation to the effect of speaking rate on interarticulator timing and interspeaker variability in inte...

Changes in formant frequencies associated with postural change in adult male speakers over 50 years old

It is possible that changes of direction of gravity relative to the vocal tract associated with changes in posture influence acoustic characteristics of speech including vowel formant frequencies. Studies examining such effects had produced mixed results and demonstrated the possibility of substantive interspeaker variability in the effect of postural changes on vowel formant frequencies. Recent work by Takakura et al. [‘‘Changes in formant frequencies associated with postural change,’’ paper presented at the Fall meeting of Acoustical Society of Japan (2006)], using young adult male speakers, revealed a small number of speakers demonstrating changes in vowel formant frequencies and suggested effect of age. The present study attempts to examine changes of vowel formant frequencies in upright and supine position among older male speakers. Attempts will be made to eliminate the effect of differences in neck position between the postures through the use of a power‐bead‐based neck stabilizer. The results will...

Articulatory characteristics of speakers with apraxia of speech during sentence production at different speaking rates

The present study developed quantitative descriptions of articulatory movements in three speakers with apraxia of speech during sentences produced at different speaking rates. Point‐parameterized articulatory data were obtained using the x‐ray microbeam (XRMB) technique, and were compared with similar materials from 24 normal young‐adult speakers of American English drawn from an existing XRMB database. Speed histories of markers attached to the lips and jaw during production of the test sentence ‘‘The other one is too big.’’ spoken at slow, habitual and fast rates were analyzed to determine mean peak speed, the number of speed peaks, and the timing of particular speed peaks for each sentence replicate by each talker. An attempt was made to derive speed histories for the lip marker expressed relative to concurrent movements of the jaw, to evaluate the relative contribution of jaw speed to lip speed in both talker groups. A description and discussion of results from the analysis will emphasize speaking rat...