The perception and production of Korean stops in second dialect acquisition.

This study investigated the acoustic cue weighting of the Korean stop contrast in the perception and production of speakers who moved from a nonstandard dialect region to the standard dialect region, Seoul. Through comparing these mobile speakers with data from nonmobile speakers in Seoul and their home region, it was found that the speakers shifted their cue weighting in perception and production to some degree, but also retained some subphonemic features of their home dialect in production. The implications of these results for the role of dialect prestige and awareness in second dialect acquisition are discussed.

Individual Differences in Categorical Judgment of L2 Stops: A Link to Proficiency and Acoustic Cue-Weighting.

This study investigated individual differences in Korean adult learners' categorical perception of L2 English stops with an aim to explore the relationship of gradient categorizations to perceptual sensitivity to acoustic cues and L2 proficiency. Korean young adult L2 learners of English (N = 49) participated in two speech perception tasks (visual analog scaling and forced-choice identification) in which they listened to English voiced and voiceless stops and Korean lax and aspirated stops with Voice Onset Time (VOT) and F0 manipulated to form a continuum. It was found that in both L1 and L2 stop perception, listeners' gradient category judgment was associated with greater reliance on language-specific redundant cues (i.e., F0 in L2 English and VOT in L1 Korean) and that in the perception of L2 stops, categorical listeners who tended to be less sensitive to F0 were the ones with a higher level of L2 English proficiency. The results suggest that the categorical manner of judging L2 stops reflects learners' better knowledge of L2-specific acoustic cue-weightings, based on which less relevant acoustic information is effectively suppressed.

Bayesian data analysis in the phonetic sciences: A tutorial introduction.

This tutorial analyzes voice onset time (VOT) data from Dongbei (Northeastern) Mandarin Chinese and North American English to demonstrate how Bayesian linear mixed models can be fit using the programming language Stan via the R package brms. Through this case study, we demonstrate some of the advantages of the Bayesian framework: researchers can (i) flexibly define the underlying process that they believe to have generated the data; (ii) obtain direct information regarding the uncertainty about the parameter that relates the data to the theoretical question being studied; and (iii) incorporate prior knowledge into the analysis. Getting started with Bayesian modeling can be challenging, especially when one is trying to model one's own (often unique) data. It is difficult to see how one can apply general principles described in textbooks to one's own specific research problem. We address this barrier to using Bayesian methods by providing three detailed examples, with source code to allow easy reproducibility. The examples presented are intended to give the reader a flavor of the process of model-fitting; suggestions for further study are also provided. All data and code are available from: https://osf.io/g4zpv.

Attentional Modulation and Individual Differences in Explaining the Changing Role of Fundamental Frequency in Korean Laryngeal Stop Perception.

Previous research has shown differential degrees of attention in processing hierarchical linguistic information where higher order cues require greater attention in speech processing. The current study investigated the influence of attentional resources on acoustic cue weightings in speech perception by examining Korean listeners' identifications of the three-way laryngeal stops (tense vs. lax vs. aspirated). Using a dual-task paradigm, we presented 28 adult Korean listeners with identification tasks blocked by no-distractor versus distractor conditions where arithmetic calculations distracted the listeners' speech processing. Auditory stimuli were prepared by combining voice-onset times (VOTs) and fundamental frequencies (F0s) based on natural production. Group analyses revealed that VOT was an informative parameter across the three stop laryngeal categories and the listeners' reliance on VOT was consistently reduced under the distracting condition. Subsequent individual-level analysis further showed that listeners with heavier perceptual reliance on VOT were hindered by the distractor more than others in utilizing VOT. Unlike VOT, the F0 cue did not systematically interact with the distracting listening condition. The findings indicated that VOT (but not F0) required greater attention in processing the Korean laryngeal stops, and was presumably a higher order acoustic cue than F0. The current study contributes to the understanding of attention and cue primacy in general as well as to the clarification of the relative roles of VOT and F0 for the Korean stop laryngeal contrast.

Evaluating the sources and functions of gradiency in phoneme categorization: An individual differences approach.

During spoken language comprehension listeners transform continuous acoustic cues into categories (e.g., /b/ and /p/). While long-standing research suggests that phonetic categories are activated in a gradient way, there are also clear individual differences in that more gradient categorization has been linked to various communication impairments such as dyslexia and specific language impairments (Joanisse, Manis, Keating, & Seidenberg, 2000; López-Zamora, Luque, Álvarez, & Cobos, 2012; Serniclaes, Van Heghe, Mousty, Carré, & Sprenger-Charolles, 2004; Werker & Tees, 1987). Crucially, most studies have used 2-alternative forced choice (2AFC) tasks to measure the sharpness of between-category boundaries. Here we propose an alternative paradigm that allows us to measure categorization gradiency in a more direct way. Furthermore, we follow an individual differences approach to (a) link this measure of gradiency to multiple cue integration, (b) explore its relationship to a set of other cognitive processes, and (c) evaluate its role in individuals' ability to perceive speech in noise. Our results provide validation for this new method of assessing phoneme categorization gradiency and offer preliminary insights into how different aspects of speech perception may be linked to each other and to more general cognitive processes. (PsycINFO Database Record

Individual differences in categorical perception of speech: Cue weighting and executive function.

This study examined individual differences in categorical perception and the use of multiple acoustic cues in the perception of the stop voicing contrast. Goals were to investigate whether gradiency of speech perception was related to listeners' differential sensitivity to acoustic cues and to individual differences in executive function. The experiment included two speech perception tasks (visual analogue scaling [VAS] and anticipatory eye movement [AEM]) administered to 30 English-speaking adults in two separate experimental sessions. Stimuli were a /ta/ to /da/ continuum that systematically varied VOT and f0. Findings were that some listeners had a more gradient pattern of responses on the VAS task; the listeners who had a gradient response pattern on the VAS task also showed more sensitivity to f0 on the AEM task. The patterns were consistent across individuals tested on two separate occasions. These results suggest that variability in how categorically listeners perceive speech sounds is consistent and systematic within individuals.

Gender difference in the affricate productions of young Seoul Korean speakers.

This study explored gender-related differences in affricates' place of articulation of young Seoul Korean speakers. Word-initial and medial affricates before /a/ and /i/ collected from 42 adult Seoul speakers were compared with alveolar and palatalized fricatives in the same vowel conditions by examining spectral peak frequencies of the frication part of the consonants. Results showed evidence of gender differences in the acoustic realization of word-medial affricates, which implies a more anterior articulation in females' productions before /a/. Possibilities for sound change in affricates led by females or the use of anterior affricates as a socially indexed gender marker are discussed.

Aligning the timelines of phonological acquisition and change.

This paper examines whether data from a large cross-linguistic corpus of adult and child productions can be used to support an assumed corollary of the Neogrammarian distinction between two types of phonological change. The first type is regular sound change, which is assumed to be incremental and so should show continuity between phonological development and the age-related variation observed in the speech community undergoing the change. The second type is dialect borrowing, which could show an abrupt discontinuity between developmental patterns before and after the socio-historical circumstances that instigate it. We examine the acquisition of two contrasts: the Seoul Korean contrast between lax and aspirated stops which is undergoing regular sound change, and the standard Mandarin contrast between retroflex and dental sibilants which has been borrowed recently into the Songyuán dialect. Acquisition of the different contrasts patterns as predicted from the assumed differences between continuous regular sound change and potentially abrupt dialect borrowing. However, there are substantial gaps in our understanding both of the extent of cross-cultural variability in language socialization and of how this might affect the mechanisms of phonological change that must be addressed before we can fully understand the relationship between the time courses of the two.

Voiced stop prenasalization in two dialects of Greek.

This study examined the phonetic realization of voiced stops in the Cretan and Thessalonikan dialects of Modern Greek. Six males and six females of each dialect were recorded in a sentence-reading task. Duration and amplitude were measured to compare the degree of nasality of voiced stops to that of nasals in different phonetic contexts. Results showed that amplitude changes during the voicing bar of the voiced stops varied both within and across speakers. In some instances, there was consistently low amplitude throughout the voicing bar (characteristic of voiced stops), whereas in other instances, there was high amplitude at the closure onset followed by decreasing amplitude toward the burst (characteristic of prenasalization). By contrast, nasals had consistently high amplitude throughout the murmur. The mixed-effects models suggest that there were complex and interactive influences of dialect, gender, prosodic position, and stress in realizing prenasality in the voiced stops. In particular, Cretan male speakers showed the least clear tendency of prenasalization consistent with earlier impressionistic studies. Furthermore, productions of Cretan males showed less prenasalization than those of females in both prosodic positions. The procedures in this study can be used to describe prenasalization in other dialects or languages where prenasalization has been observed.

Voice onset time is necessary but not always sufficient to describe acquisition of voiced stops: The cases of Greek and Japanese.

The age at which children master adult-like voiced stops can generally be predicted by voice onset time (VOT): stops with optional short lag are early, those with obligatory lead are late. However, Japanese voiced stops are late despite having a short lag variant, whereas Greek voiced stops are early despite having consistent voicing lead. This cross-sectional study examines the acoustics of word-initial stops produced by English-, Japanese-, and Greek-speaking children aged 2 to 5, to investigate how these seemingly exceptional mastery patterns relate to use of other phonetic correlates. Productions were analyzed for VOT, f0 and spectral tilt (H1-H2) in Japanese and English, and for amplitude trajectory in Greek and Japanese. Japanese voiceless stops have intermediate lag VOT values, so other "secondary" cues are needed to differentiate them from the voiced short lag VOT variant. Greek voiced stops are optionally prenasalized, and the amplitude trajectory for the voice bar during closure suggests that younger children use a greater degree of nasal venting to create the aerodynamic conditions necessary for voicing lead. Taken together, the findings suggest that VOT must be supplemented by measurements of other language-specific acoustic properties to explain the mastery pattern of voiced stops in some languages.

Cross-linguistic studies of children's and adults' vowel spaces.

This study examines cross-linguistic variation in the location of shared vowels in the vowel space across five languages (Cantonese, American English, Greek, Japanese, and Korean) and three age groups (2-year-olds, 5-year-olds, and adults). The vowels /a/, /i/, and /u/ were elicited in familiar words using a word repetition task. The productions of target words were recorded and transcribed by native speakers of each language. For correctly produced vowels, first and second formant frequencies were measured. In order to remove the effect of vocal tract size on these measurements, a normalization approach that calculates distance and angular displacement from the speaker centroid was adopted. Language-specific differences in the location of shared vowels in the formant values as well as the shape of the vowel spaces were observed for both adults and children.

Why are Korean tense stops acquired so early: The role of acoustic properties.

Transcription-based studies have shown that tense stops appear before aspirated or lax stops in most Korean-acquiring children's speech. This order of mastery is predicted by the short lag Voice Onset Time (VOT) values of Korean tense stops, as this is the earliest acquired phonation type across languages. However, the tense stop also has greater motor demands than the other two phonation types, given its pressed voice quality (negative H1-H2) and its relatively high f0 value at vowel onset, word-initially. In order to explain the observed order of mastery of Korean stops, we need a more sensitive quantitative model of the role of multiple acoustic parameters in production and perception. This study explores the relationship between native speakers' transcriptions/categorizations of children's stop productions and three acoustic characteristics (VOT, H1-H2 and f0). The results showed that the primary acoustic parameter that adult listeners used to differentiate tense vs. non-tense stops was VOT. Listeners used VOT and the additional acoustic parameter of f0 to differentiate lax vs. aspirated stops. Thus, the early acquisition of tense stops is explained both by their short-lag VOT values and the fact that children need to learn to control only a single acoustic parameter to produce them.