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Paper short abstract

VOT data from 103 young speakers across eastern Japan reveal three regional laryngeal patterns, including an aspiration-like system in Tohoku. These findings suggest that voicing- and aspiration-based contrasts can coexist and may be derived from a unified representation.

Paper long abstract

This study investigates the phonological representation of laryngeal source contrasts in Japanese and the regional variation found among younger speakers in eastern Japan. Cross-linguistically, word-initial obstruents are often used to diagnose laryngeal contrasts because this position is prosodically strong and exhibits relatively stable phonetic cues compared with weaker environments such as intervocalic or word-final positions. Previous typological research has examined these contrasts using a range of acoustic parameters, including voice onset time (VOT) (Lisker & Abramson 1964), low-frequency energy reduction during closure, and the presence or absence of F1 cutback.

Within Element Theory (Harris 1994; Backley 2011), stop contrasts are represented with combinations of |ʔ| (closure), |H| (frication/aspiration), and |L| (voicing). Voiceless unaspirated stops (0 VOT) correspond to |ʔH|, voiced stops (−VOT) to |ʔHL|, and voiceless aspirated stops (+VOT) to |ʔHH|. Two-way laryngeal systems are therefore classified either as voicing languages, contrasting |ʔH| and |ʔHL|, or aspiration languages, contrasting |ʔH| and |ʔHH|. Although Japanese has long been analysed as a voicing language (Shimizu 1996), the classification has not been systematically re-examined for younger speakers across different regions.

To address this gap, we measured word-initial VOT values for /b d g/ and /p t k/ produced by 103 native speakers (mean age 20.8 ± 2.4) from Tohoku, Kanto, Chubu, and neighbouring regions. A hierarchical cluster analysis based on mean VOT values revealed three major patterns: Cluster 1 (primarily Kanto–Chubu) showed −17.7 ms for voiced stops and 42.2 ms for voiceless stops; Cluster 2 (Kanto–Hokuriku–Tohoku) showed slightly positive VOT for voiced stops (8.9 ms) with slightly longer voiceless values (42.2 ms); and Cluster 3 (mainly Tohoku) showed consistently positive VOT for voiced stops (15.1 ms) and markedly longer VOT for voiceless stops (59.3 ms). The third pattern points toward an aspiration-type contrast, partly consistent with Takada (2011).

To capture this internally conditioned variation, we propose a unified underlying representation combining properties of |H| and |L|, with regional outcomes derived through selective suppression of one element. Suppressing |L| yields |ʔH| (/d/-like), while suppressing |H| yields |ʔH| (/t/-like). This model predicts that aspiration- and voicing-based systems may coexist within Japanese.

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Paper short abstract

This study examines how vowel duration affects the intelligibility and accentedness of Japanese produced by Polish speakers. Using PSOLA manipulations and native listener evaluations, results show that correcting vowel length significantly improves both intelligibility and accent ratings.

Paper long abstract

This study investigates the role of vowel duration in the phonemic contrast between short and long vowels in Japanese. Nine native Polish speakers produced minimal pairs differing only in vowel length. Using the PSOLA function in Praat, these recordings were manipulated to match native Japanese vowel durations. Both unmanipulated and manipulated stimuli were then used in a perception experiment hosted on the Gorilla Experiment Builder.

Twenty-four native Japanese listeners completed two tasks: an intelligibility task (four-alternative forced-choice) and an accentedness task (7-point Likert scale). The experiment included 120 test trials and 30 filler items from native Japanese speakers.

Initial acoustic analysis revealed that Polish speakers generally produced both short and long vowels with durations exceeding native norms. While most preserved the short-to-long ratio, some speakers exhibited ratios that were either too small or too large.

Statistical analysis using a logistic regression model for the intelligibility task showed that adjusting vowel durations to native-like realizations significantly increased accuracy from 72% in the unmanipulated condition to 89% in the manipulated condition. For accentedness, a linear mixed-effects model revealed that duration manipulation predicted a significant 0.5-point increase on the Likert scale.

These findings suggest that while vowel duration is a primary cue for word recognition, it also serves as a significant marker of nativeness. The study contributes to the literature on L2 speech perception and highlights the necessity of prioritizing temporal accuracy in Japanese pronunciation pedagogy for Polish learners.

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Paper short abstract

This study shows that, despite the absence of length distinction in Polish, Polish speakers can produce closure-duration contrasts in Japanese word-medial plosives, highlighting the role of language-specific phonetic experience in second language cue acquisition.

Paper long abstract

Japanese native speakers rely heavily on closure duration as a key acoustic cue in both the production and perception of word-medial plosive voicing contrasts. In contrast, Polish lacks a phonemic length distinction, and previous studies have shown that Polish speakers experience difficulty acquiring temporally based contrasts, such as pre-fortis clipping in English. This background raises the question of whether Polish speakers are able to acquire and implement the temporal cues required for Japanese word-medial voicing contrasts. The present study addresses this issue by examining whether Polish native speakers can produce categorical closure-duration differences between voiced and voiceless Japanese word-medial plosives, with English and Chinese learners included as reference groups for cross-linguistic comparison.

A controlled recording experiment was conducted with 8 Polish, 10 Japanese, 10 Chinese, and 4 English speakers. Participants produced nine real-word minimal pairs contrasting in word-medial plosive voicing (three pairs for each place of articulation), embedded in a carrier sentence. All non-native participants were advanced learners of Japanese. Acoustic analyses focused on voicing realization and closure duration in order to assess both the presence of categorical contrasts and the magnitude of temporal differences between voiced and voiceless plosives.

The results show that Polish native speakers consistently produced clear between-category voicing distinctions in Japanese word-medial plosives. Importantly, they were also able to realize systematic closure-duration differences for most plosive pairs. The magnitude of these temporal contrasts was comparable to that observed in native Japanese speakers, though smaller than those produced by English speakers. Chinese speakers, by contrast, showed limited evidence of reliable closure-duration differences across most plosive pairs. Additional results from detailed acoustic analyses, including voice onset time and burst-related measures, will also be presented.

Taken together, these findings suggest that Polish speakers can acquire the temporal implementation of Japanese voicing contrasts despite the absence of phonemic length distinctions in their native language. The study highlights the role of language-specific phonetic experience in second-language speech production and provides detailed acoustic evidence for cross-linguistic differences in cue acquisition.

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Paper short abstract

Slovenian has largely lost phonemic vowel length and use duration suprasegmentally to mark stress. Slovenian learners of Japanese master long–short contrasts but systematically reinterpret certain trimoraic CV–CV–R words as CV–R–CV, demonstrating prosodic transfer affecting L2 segmental structure.

Paper long abstract

In most Slovene dialects, vowel length no longer functions as a phonemic feature at the segmental level. The historical long–short contrast has been lost, and vowel duration is instead used at the suprasegmental level to cue stress placement and accentual prominence.

In contrast, Japanese encodes vowel length phonemically, and minimal pairs such as 通る tōru ‘pass by’ and 取る toru ‘take’ illustrate that vowel duration is contrastive at the moraic level and independent of stress or accent placement. Slovenian learners of Japanese generally acquire this contrast successfully and produce phonemic vowel length accurately in most lexical contexts.

However, a systematic deviation has been observed at the beginner level in the production of certain disyllabic, trimoraic Japanese words containing a sequence of identical vowels in the second syllable (CV–CV–R). Based on both controlled and spontaneous speech data, these forms are occasionally realized as CV–R–CV, yielding outputs that preserve the overall mora count but alter the mora–segment association. Crucially, this reordering occurs only under specific prosodic conditions, namely when the initial mora lacks lexical pitch accent. Thus, the target form 旅行 ryokō ‘a trip’ may surface as [rjoːko], rendering it homophonous with the female given name Ryōko.

This pattern suggests a reanalysis of L2 Japanese vowel length as a suprasegmental rather than a segmental property. The study systematically examines the influence of Slovene accentual representations on this non-target-like pronunciation and argues that learners reinterpret the long vowel not as a bimoraic vowel linked to a single syllabic nucleus, but as a prosodic lengthening effect associated with the most prominent unit in the word. This reinterpretation reflects transfer from the Slovene prosodic system, in which durational cues are systematically tied to stress rather than lexically specified at the segmental level.

The findings demonstrate that suprasegmental interference may give rise to non-target-like segmental outputs, even in cases where learners appear to have acquired the relevant contrast. Pedagogically, these findings underscore the need to explicitly represent moraic structure in teaching Japanese pronunciation to Slovene learners.

Keywords: vowel length, moraic structure, suprasegmental transfer, L2 phonological acquisition, Slovene–Japanese prosodic interference