Variation in /u/ fronting in the American Midwest.

Previous research has suggested that a greater degree of social indexing of gender, race, and regional background is produced in linguistic contexts that promote phonetic reduction. The goal of the current study was to explore this hypothesis through an examination of the realization of an ongoing sound change in the American Midwest-/u/ fronting-as a function of four linguistic factors that contribute to phonetic reduction: lexical frequency, phonological neighborhood density, discourse mention, and speaking style. The results revealed minimal effects of the linguistic factors on the degree of /u/ fronting among talkers with greater overall advancement in the /u/ fronting change-in-progress, suggesting that the process of /u/ fronting is nearing completion among some American Midwesterners. However, the results also revealed more /u/ fronting in plain laboratory speech than in clear laboratory speech and in low-frequency, low-density words than in low-frequency, high-density words among talkers with lower overall advancement in the /u/ fronting change-in-progress. The directions of these effects are consistent with the hypothesis that social indexing is greater in reduction-promoting contexts. Further, the relative sizes of these effects suggest that speaking style contributes more to variability in social indexing than lexical properties, such as frequency and neighborhood density.

K-SPAN: A lexical database of Korean surface phonetic forms and phonological neighborhood density statistics.

This article presents K-SPAN (Korean Surface Phonetics and Neighborhoods), a database of surface phonetic forms and several measures of phonological neighborhood density for 63,836 Korean words. Currently publicly available Korean corpora are limited by the fact that they only provide orthographic representations in Hangeul, which is problematic since phonetic forms in Korean cannot be reliably predicted from orthographic forms. We describe the method used to derive the surface phonetic forms from a publicly available orthographic corpus of Korean, and report on several statistics calculated using this database; namely, segment unigram frequencies, which are compared to previously reported results, along with segment-based and syllable-based neighborhood density statistics for three types of representation: an "orthographic" form, which is a quasi-phonological representation, a "conservative" form, which maintains all known contrasts, and a "modern" form, which represents the pronunciation of contemporary Seoul Korean. These representations are rendered in an ASCII-encoded scheme, which allows users to query the corpus without having to read Korean orthography, and permits the calculation of a wide range of phonological measures.

The Role of Predictability in Intonational Variability.

Predictability is known to affect many properties of speech production. In particular, it has been observed that highly predictable elements (words, syllables) are produced with less phonetic prominence (shorter duration, less peripheral vowels) than less predictable elements. This tendency has been proposed to be a general property of language. This paper examines whether predictability is correlated with fundamental frequency (F0) production, through analysis of experimental corpora of American English. Predictability was variously defined as discourse mention, utterance probability, and semantic focus. The results revealed consistent effects of utterance probability and semantic focus on F0, in the expected direction: less predictable words were produced with a higher F0 than more predictable words. However, no effect of discourse mention was observed. These results provide further empirical support for the generalization that phonetic prominence is inversely related to linguistic predictability. In addition, the divergent results for different predictability measures suggests that the parameterization of predictability within a particular experimental design can have significant impact on the interpretation of results, and that it cannot be assumed that two measures necessarily reflect the same cognitive reality.

Constraints of Tones, Vowels and Consonants on Lexical Selection in Mandarin Chinese.

Previous studies have shown that when speakers of European languages are asked to turn nonwords into words by altering either a vowel or consonant, they tend to treat vowels as more mutable than consonants. These results inspired the universal vowel mutability hypothesis: listeners learn to cope with vowel variability because vowel information constrains lexical selection less tightly and allows for more potential candidates than does consonant information. The present study extends the word reconstruction paradigm to Mandarin Chinese--a Sino-Tibetan language, which makes use of lexically contrastive tone. Native speakers listened to word-like nonwords (e.g., su3) and were asked to change them into words by manipulating a single consonant (e.g., tu3), vowel (e.g., si3), or tone (e.g., su4). Additionally, items were presented in a fourth condition in which participants could change any part. The participants' reaction times and responses were recorded. Results revealed that participants responded faster and more accurately in both the free response and the tonal change conditions. Unlike previous reconstruction studies on European languages, where vowels were changed faster and more often than consonants, these results demonstrate that, in Mandarin, changes to vowels and consonants were both overshadowed by changes to tone, which was the preferred modification to the stimulus nonwords, while changes to vowels were the slowest and least accurate. Our findings show that the universal vowel mutability hypothesis is not consistent with a tonal language, that Mandarin tonal information is lower-priority than consonants and vowels and that vowel information most tightly constrains Mandarin lexical access.

Development and Validation of a Flexible Sensing Array for Placement within the Physical Human-Exoskeleton Interface.

Monitoring the human-exoskeleton interface (HEI) is vital for user safety in assistive exoskeletons. Considering interaction forces during design can improve comfort and efficiency and reduce resistance and inertia. Challenges include covering the lower limb area without interfering with user-robot interaction. This paper presents a force-sensitive resistor (FSR) based sensing sleeve for use within the HEI. The design includes 30 sensors and works independently of it to assess attachment modalities. System characterisation tests the system with human trials. Demonstrating that a low-cost, flexible sensing array can accurately monitor HEI. This provides a promising tool for assessing human-robot interaction and investigating wearable robotic device use.

Patterns of individual differences in the perception of missing-fundamental tones.

Recent experimental findings suggest stable individual differences in the perception of auditory stimuli lacking energy at the fundamental frequency (F0), here called missing fundamental (MF) tones. Specifically, some individuals readily identify the pitch of such tones with the missing F0 ("F0 listeners"), and some base their judgment on the frequency of the partials that make up the tones ("spectral listeners"). However, the diversity of goals and methods in recent research makes it difficult to draw clear conclusions about individual differences. The first purpose of this article is to discuss the influence of methodological choices on listeners' responses. The second goal is to report findings on individual differences in our own studies of the MF phenomenon. In several experiments, participants judged the direction of pitch change in stimuli composed of two MF tones, constructed so as to reveal whether the pitch percept was based on the MF or the partials. The reported difference between F0 listeners and spectral listeners was replicated, but other stable patterns of responses were also observed. Test-retest reliability is high. We conclude that there are genuine, stable individual differences underlying the diverse findings, but also that there are more than two general types of listeners, and that stimulus variables strongly affect some listeners' responses. This suggests that it is generally misleading to classify individuals as "F0 listeners" or "spectral listeners." It may be more accurate to speak of two modes of perception ("F0 listening" and "spectral listening"), both of which are available to many listeners. The individual differences lie in what conditions the choice between the two modes.