Ishida, Mako

写真a

Affiliation

Faculty of Science and Technology, Department of Foreign Languages and Liberal Arts (Hiyoshi)

Position

Assistant Professor/Senior Assistant Professor

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Papers 【 Display / hide 】

  • Perceptual restoration of degraded speech: The effects of linguistic structure

    Ishida M., Arai T., Kashino M.

    Attention, Perception, & Psychophysics  2025.08

    ISSN  1943-3921

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    <jats:title>Abstract</jats:title>
    <jats:p>Listeners can understand speech even when its temporal structure is acoustically distorted. Ishida et al. (<jats:italic>Frontiers in Psychology, 9</jats:italic>, 1749, 2018) reported that native English speakers could comprehend English sentences using two types of temporal distortions: (1) speech signals divided into equally timed segments, with each segment reversed in time (locally time-reversed speech), and (2) speech signals with reduced modulation-frequency components shaping the amplitude envelope (modulation-filtered speech). While the results showed a similar pattern of intelligibility decline across these two conditions in English (a syllable-oriented language with consonant clusters) when degradation increased in six steps, it remained unclear whether this pattern holds in a linguistically distinct language like Japanese (a mora-oriented language with CV and V as basic linguistic units). The current study investigates how native Japanese speakers comprehend Japanese sentences under the same temporal distortions. In Experiment 1, participants listened to locally time-reversed Japanese sentences with segment intervals reversed at 10 ms, 30 ms, 50 ms, 70 ms, 90 ms, and 110 ms. In Experiment 2, the same participants listened to modulation-filtered Japanese sentences, where the modulation frequency components were low-pass filtered at cut-off frequencies of 32 Hz, 16 Hz, 8 Hz, 4 Hz, 2 Hz, and 1 Hz. Results showed that the intelligibility of locally time-reversed and modulation-filtered Japanese sentences decreased as distortion increased, with longer reversed segment lengths and lower cut-off frequencies. However, the patterns of intelligibility degradation in Japanese differed significantly from those in English. Thus, perceptual restoration may function differently depending on the basic linguistic units (mora vs. syllable).</jats:p>

  • Perceptual restoration of locally time-reversed speech: Japanese words are very tolerant of severe temporal distortion

    Ishida M., Arai T., Kashino M.

    Attention, Perception, &amp; Psychophysics  2025.07

    ISSN  1943-3921

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    <jats:title>Abstract</jats:title>
    <jats:p>People can understand speech even when the speech signal is divided into equally long segments and each segment is reversed in time (locally time-reversed speech). In addition, Ishida (<jats:italic>Attention, Perception &amp; Psychophysics, 83</jats:italic>(6), 2675–2693, 2021) reported that Japanese words – composed of consonant–vowel (CV) units – were significantly more intelligible than English words when locally time-reversed. The current study investigates how tolerant and robust Japanese words are under more severe temporal distortions. In Experiment 1, native Japanese speakers listened to Japanese words and pseudowords that were locally time-reversed at intervals of 100, 120, 140, 160, 180, and 200 ms, which had not been previously examined. These lexical items contained either many fricatives or stops. Results showed that Japanese words were highly tolerant of local time reversal, even at these extreme durations. Perceptual restoration was sustained by dominant phoneme type (fricative-dominant &gt; stop-dominant) and lexicality (words &gt; pseudowords). In Experiment 2, participants listened to <jats:italic>stop-dominant</jats:italic> Japanese words and pseudowords, which were more susceptible to temporal distortion in Experiment 1. Temporal distortion was further increased by introducing extreme speech rates (fast vs. slow) while reversing the signal at 10, 30, 50, 70, 90, and 110 ms, commonly used intervals with normal speech rates. Results showed that <jats:italic>stop-dominant</jats:italic> Japanese words remained intelligible with increasing distortions, while pseudowords remained intelligible only up to 50 ms in the slow condition and became unintelligible in the fast condition. Overall, recognition of Japanese CV-based words was highly tolerant of severe temporal distortion, with perceptual restoration supported by dominant phoneme type, slower speech rate, and lexicality.</jats:p>

  • Perceptual restoration of locally time-reversed speech: Non-native listeners' performance in their L2 vs. L1.

    Ishida M

    Attention, perception & psychophysics 83 ( 6 ) 2675 - 2693 2021.08

    ISSN  1943-3921

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    Nonnative listeners are generally not as good as native listeners in perceptually restoring degraded speech and understand what was being said. The current study investigates how nonnative listeners of English (namely, native Japanese speakers who learned English as a second language) perceptually restore temporally distorted speech in their L2 English as compared with native English listeners (L1 English) reported in Ishida et al. (Cognition, 151, 68-75, 2016), and as compared with the listeners' native tongue (L1 Japanese). In the experiment, listeners listened to locally time-reversed words and pseudowords in their L2 English and L1 Japanese where every 10, 30, 50, 70, 90, or 110 ms of speech signal was flipped in time-these stimuli contained either many fricatives or stops. The results suggested that the intelligibility of locally time-reversed words and pseudowords deteriorated as the length of reversed segments increased in both listeners' L2 English and L1 Japanese, while listeners understood locally time-reversed speech more in their L1 Japanese. In addition, lexical context supported perceptual restoration in both listeners' L1 Japanese and L2 English, while phonemic constituents affected perceptual restoration significantly only in listeners' L1. On the other hand, locally time-reversed words and pseudowords in L1 Japanese were much more intelligible than those in L1 English reported in Ishida et al. It is possible that the intelligibility of temporally distorted lexical items depends on the structure of basic linguistic units in each language, and the Japanese language might have a unique characteristic because of its CV and V structure.

  • Perceptual restoration of temporally distorted speech in L1 vs. L2: Local time reversal and modulation filtering

    Ishida M., Arai T., Kashino M.

    Frontiers in Psychology (Frontiers in Psychology)  9 ( SEP )  2018.09

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    Speech is intelligible even when the temporal envelope of speech is distorted. The current study investigates how native and non-native speakers perceptually restore temporally distorted speech. Participants were native English speakers (NS), and native Japanese speakers who spoke English as a second language (NNS). In Experiment 1, participants listened to "locally time-reversed speech" where every x-ms of speech signal was reversed on the temporal axis. Here, the local time reversal shifted the constituents of the speech signal forward or backward from the original position, and the amplitude envelope of speech was altered as a function of reversed segment length. In Experiment 2, participants listened to "modulation-filtered speech" where the modulation frequency components of speech were low-pass filtered at a particular cut-off frequency. Here, the temporal envelope of speech was altered as a function of cut-off frequency. The results suggest that speech becomes gradually unintelligible as the length of reversed segments increases (Experiment 1), and as a lower cut-off frequency is imposed (Experiment 2). Both experiments exhibit the equivalent level of speech intelligibility across six levels of degradation for native and non-native speakers respectively, which poses a question whether the regular occurrence of local time reversal can be discussed in the modulation frequency domain, by simply converting the length of reversed segments (ms) into frequency (Hz).

  • Simultaneous articulatory and acoustic distortion in L1 and L2 Listening: Locally time-reversed "fast" speech

    Ishida M.

    Proceedings of the Annual Conference of the International Speech Communication Association, INTERSPEECH (Proceedings of the Annual Conference of the International Speech Communication Association, INTERSPEECH)  2017-August   571 - 575 2017

    ISSN  2308457X

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    The current study explores how native and non-native speakers cope with simultaneous articulatory and acoustic distortion in speech perception. The articulatory distortion was generated by asking a speaker to articulate target speech as fast as possible (fast speech). The acoustic distortion was created by dividing speech signals into small segments with equal time duration (e.g., 50 ms) from the onset of speech, and flipping every segment on a temporal axis, and putting them back together (locally time-reversed speech). This study explored how "locally time-reversed fast speech" was intelligible as compared to "locally time-reversed normal speech" measured in Ishida, Samuel, and Arai (2016). Participants were native English speakers and native Japanese speakers who spoke English as a second language. They listened to English words and pseudowords that contained a lot of stop consonants. These items were spoken fast and locally time-reversed at every 10, 20, 30, 40, 50, or 60 ms. In general, "locally time-reversed fast speech" became gradually unintelligible as the length of reversed segments increased. Native speakers generally understood locally time-reversed fast spoken words well but not pseudowords, while non-native speakers hardly understood both words and pseudowords. Language proficiency strongly supported the perceptual restoration of locally time-reversed fast speech.

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Papers, etc., Registered in KOARA 【 Display / hide 】

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

  • Perceptual restoration in the first and second language

    2021.04
    -
    2026.03

    Mako Ishida, Grant-in-Aid for Early-Career Scientists, Principal investigator

  • Speech perception and phonemic restoration by native and non-native speakers

    2017.04
    -
    2020.03

    Mako Ishida, Grant-in-Aid for JSPS Fellows, Principal investigator

  • Speech perception (phonemic restoration) by second language learners

    2015.04
    -
    2017.03

    Mako Ishida, Grant-in-Aid for JSPS Fellows, Principal investigator

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Works 【 Display / hide 】

  • PONS mobil Wortschatztraining Japanisch

    Kayo Funatsu-Böhler, Hiroyuki Ota, Karin Adam, Toshiko Arai-Sixt, Bettina Höfels, Mako Ishida, Daisuke Kadono

    2008

    　View Details

    DNB: 1193169232
    URN: urn:nbn:de:101:1-2019082121495576594529
    https://d-nb.info/1193169232

    ISBN: 978-3-12-561417-8
    DNB: 1078747857
    URN: urn:nbn:de:101:1-201511121703
    https://d-nb.info/1078747857

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Courses Taught 【 Display / hide 】

  • GLOBAL LEADERSHIP SEMINAR

    2025

  • ENGLISH SPEAKING 2

    2025

  • ENGLISH 2

    2025

  • ENGLISH 1

    2025

  • DISCUSSION IN ENGLISH 4

    2025

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