Volume 6, Issue 3-4 - Special issue title: Corpus-based approaches to the phonological analysis of speech, Guest editors: Haruo Kubozono, Kikuo Maekawa and Timothy J. Vance

Theoretical frameworks of phonology are built largely on the basis of idealized speech, typically recorded in a laboratory under static conditions. Natural speech, in contrast, occurs in a variety of communicative contexts where speakers and hearers dynamically adjust their speech to fit their needs. The present paper demonstrates that phonologically informed analysis of specialized speech registers, such as infant-directed speech, can reveal specific ways segmental and supra-segmental aspects of phonology are modulated dynamically to accommodate the specific communicative needs of speakers and hearers. Data for the analyses come from a corpus of Japanese mothers’ spontaneous speech directed to their infant child (infant-directed speech, IDS) and an adult (adult-directed speech, ADS), as well as read speech (RS). The speech samples in the corpus are annotated with segmental, morphological, and intonational information. We will show that the way intonation is exaggerated in Japanese IDS reflects the intonational structure of Japanese, which is different from that of English. We will also demonstrate that rules of phonological grammar, such as devoicing of high vowels and non-high vowels in Japanese, can be differently affected by the needs of the speaker to accommodate the specific characteristics of the listener.

Words produced to infants exhibit phonetic modifications relative to speech to adult interlocutors, such as longer, more canonical segments and prosodic enhancement. Meanwhile, within speech directed towards adults, phonetic variation is conditioned by word properties: lower word frequency and higher phonological neighborhood density (ND) correlate with increased hyperarticulation and degree of coarticulation. Both of these types of findings have interpretations that recruit listener-directed motivations, suggesting that talkers modify their speech in an effort to enhance the perceptibility of the speech signal. In that vein, the present study examines lexically-conditioned variation in infant-directed speech. Specifically, we predict that the adult-reported age at which a word was learned – lexical age-of-acquisition (AoA) – conditions phonetic variation in infant-directed speech. This prediction is indeed borne out in spontaneous infant-directed speech: later-acquired words are produced with more hyperarticulated vowels and a greater degree of nasal coarticulation. Meanwhile, ND predicts phonetic variation in data from spontaneous adult-directed speech, while AoA does not independently influence production. The patterns of findings in the current study support the stance that evaluation of the need for clarity is tuned to the listener. Lexical difficulty is evaluated by AoA in infant-directed speech, while ND is most relevant in adult-directed speech.

In this study, we investigated segment lengthening in spontaneous Japanese based on a quantitative analysis of a large-scale corpus, focusing on the following three locations at which lengthening frequently occurs: the final segments of (i) clause-initial preface tokens (fillers and conjunctions), (ii) clause-initial wa -marked topic phrases, and (iii) clause-final particles. Two cognitive factors, namely clause complexity and boundary depth, were precisely analyzed using statistical models that also accounted for several phonological and syntactic factors. The results showed that in addition to the reliably strong effects of some phonological factors such as the presence of a following pause and the presence of boundary pitch movement, the effects of two cognitive factors were also evident. The way in which lengthening is related to the cognitive factors, however, varies significantly by location and token type. Lengthening of clause-final particles was affected by boundary depth, while lengthening of the topic marker wa of clause-initial topic phrases was influenced by clause complexity. Lengthening of the filler e was affected by both factors. A significant interaction between the two factors was also observed for the filler ano . We discuss the implications of these results as well as agendas for improving the current analysis.

Transcribers make mistakes. Workers recruited in a crowdsourcing marketplace, because of their varying levels of commitment and education, make more mistakes than workers in a controlled laboratory setting. Methods for compensating transcriber mistakes are desirable because, with such methods available, crowdsourcing has the potential to significantly increase the scale of experiments in laboratory phonology. This paper provides a brief tutorial on statistical learning theory, introducing the relationship between dataset size and estimation error, then presents a theoretical description and preliminary results for two new methods that control labeler error in laboratory phonology experiments. First, we discuss the method of crowdsourcing over error-correcting codes. In the error-correcting-code method, each difficult labeling task is first factored, by the experimenter, into the product of several easy labeling tasks (typically binary). Factoring increases the total number of tasks, nevertheless it results in faster completion and higher accuracy, because workers unable to perform the difficult task may be able to meaningfully contribute to the solution of each easy task. Second, we discuss the use of explicit mathematical models of the errors made by a worker in the crowd. In particular, we introduce the method of mismatched crowdsourcing, in which workers transcribe a language they do not understand, and an explicit mathematical model of second-language phoneme perception is used to learn and then compensate their transcription errors. Though introduced as technologies that increase the scale of phonology experiments, both methods have implications beyond increased scale. The method of easy questions permits us to probe the perception, by untrained listeners, of complicated phonological models; examples are provided from the prosody of English and Hindi. The method of mismatched crowdsourcing permits us to probe, in more detail than ever before, the perception of phonetic categories by listeners with a different phonological system.

Our study presents the initial results of an analysis of North Frisian intonation, based on a spontaneous interview corpus of Fering, the dialect of the island of Föhr off the west coast of the German state of Schleswig-Holstein. The corpus was recorded more than 50 years ago during fieldwork for language documentation and conservation purposes. We selected a small part of this corpus – interviews of 10 elderly speakers – and conducted multiparametric F 0 and duration measurements, focusing on nuclear rising-falling pitch accent patterns. We found strong evidence for a phonological pitch-accent distinction that relies on the difference between a pointed and a plateau-shaped F 0 peak. We suggest that the two pitch accents be represented as L+H* and H*+L, and we discuss our findings with regard to possible communicative functions, implications for intonational typology, and the trade-off between F 0 range and F 0 peak extension in conveying pitch height.

This paper presents an apparent-time study of the vowel length contrast merger in Seoul Korean based on duration measurements of over 370,000 vowels in word-initial syllables in a read-speech corpus. The effects of word frequency on vowel duration and the lexical diffusion of long-vowel shortening are also examined. The findings confirm the observation made in the previous literature that the vowel length contrast is on its way out in the language, and that this sound change is nearing completion. We also find a significant effect of frequency on long-vowel duration: other things being equal, these vowels are shorter in high-frequency words than in low-frequency words. The rate of change does not differ significantly depending on the frequency of words apart from the high-frequency words reaching the endpoint of change and bottoming out in the change earlier than mid- and low-frequency words. The observed frequency effect is compatible with a model in which the frequency effect on duration comes from on-line factors that affect phonetic implementation of speech sounds, along with an across-the-board lenition bias that drives the sound change, not from stored tokens of word-specific variants.

While voice onset time (VOT) is known to be sensitive to a range of phonetic and linguistic factors, much less is known about VOT in spontaneous speech, since most studies consider stops in single words, in sentences, and/or in read speech. Scottish English is typically said to show less aspirated voiceless stops than other varieties of English, but there is also variation, ranging from unaspirated stops in vernacular speakers to more aspirated stops in Scottish Standard English; change in the vernacular has also been suggested. This paper presents results from a study which used a fast, semi-automated procedure for analyzing positive VOT, and applied it to stressed syllable-initial stops from a real- and apparent-time corpus of naturally-occurring spontaneous Glaswegian vernacular speech. We confirm significant effects on VOT for place of articulation and local speaking rate, and trends for vowel height and lexical frequency. With respect to time, our results are not consistent with previous work reporting generally shorter VOT in elderly speakers, since our results from models which control for local speech rate show lengthening over real-time in the elderly speakers in our sample. Overall, our findings suggest that VOT in both voiceless and voiced stops is lengthening over the course of the twentieth century in this variety of Scottish English. They also support observations from other studies, both from Scotland and beyond, indicating that gradient shifts along the VOT continuum reflect subtle sociolinguistic control.