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A previous study found that spatial release from masking (SRM) could be observed under virtual reverberant environments using a first order Ambisonic-based sound reproduction system, however, poor localisation accuracy made it difficult to examine effect of varying reverberation time on SRM. The present study follows on using higher order Ambisonics (HOA) to examine how benefits from SRM vary in different spatial acoustics. Subjective speech intelligibility was measured where four room acoustics:reverberation time (RT)= 0.7 s (clarity (C50)= 16 dB, 7 dB); RT= 1.8 s (C50= 8 dB, 2 dB) were simulated via a third order Ambisonic system with a 16 channel spherical loudspeaker array. The masker was played from 8 azimuthal angles (0, +-45, +-90, +-135, 180 degrees) while the target speech was played from 0 degree. The listeners are deemed to benefit from SRM if their intelligibility scores were higher when the masker comes from a different angle than that of the target. We found while listeners could benefit from SRM at C50 = 16 dB and 8 dB, the benefit starts to diminish at C50 = 7 dB, and listeners could no longer benefit from SRM at C50 = 2 dB.

An ongoing debate in the speech production literature suggests that the initial building block to build up speech sounds differs between languages. That is, Germanic languages are suggested to use the phoneme, but Japanese and Chinese are proposed to use the mora or syllable, respectively. Several studies investigated this matter from a chronometric perspective (i.e., RTs and accuracy). However, a less attention has been paid to the actual acoustic utterances. The current study investigated the verbal responses of two Japanese-English bilingual groups of different proficiency levels (i.e., high and low) when naming English words and found that the presence or absence of vowel epenthesis depended on proficiency. The results indicate that: (1) English word pronunciation by low-proficient Japanese English bilinguals is likely based on their L1 (Japanese) building block and (2) that future studies would benefit from analyzing the acoustic data as well when making inferences from chronometric data.

The current paper examines how native and non-native listeners of New Zealand English differ in terms of speech intelligibility in noise in a number of room acoustics reproduced by a first-order Ambisonics-based sound reproduction system. Speech intelligibility test was conducted under three room acoustics environments (living room, lecture theatre and church) using the sound reproduction system, where a pink noise masker was played from one of five azimuthal angles (0, 45, 90, 135, 180°) while the target speech was always played from 0°. We found significant two-way interactions between language nativeness and speech-noise separation, language nativeness and room acoustics, as well as between room acoustics and speech-noise separation. This suggests that native and non-native listeners respond differently to the virtually reproduced acoustic environments and they benefit from spatial release from masking in a different manner. Post-hoc results showed the native listeners performing significantly better than their non-native counterparts for all the angles of speech-noise separation and the room acoustics.

Previous research on the perception of consonant clusters by Japanese native speakers has revealed that they are highly likely to perceive a vowel between the two consonants even if there are no vowels inserted (Dupoux et al. 1999). The present study further investigates this issue but by dividing the group of Japanese native speakers into two groups: Japanese-English bilinguals and Japanese monolinguals. This study aims to look into the influence of language learning experience on the perception of foreign sounds. Results of the perception test revealed that bilinguals made less error than monolinguals in identifying pseudowords with and without consonant cluster.

The present study investigates the effect of noise on speech intelligibility under an Ambisonics-based sound reproduction system, which is a commonly used technique for realising audio virtual reality. The sound reproduction system was built in an anechoic chamber using a 16 channel spherical loudspeaker array. A commercially available first-order Ambisonics microphone array was utilised for collecting room impulse responses of rooms with different acoustic characteristics, and a decoder for generating signals rendered from the loudspeaker array. A subjective listening test was conducted in the sound reproduction system examining how intelligibility of sentences is compromised by noise under virtually reproduced acoustics environments with various acoustical conditions. Particular focus was given to investigating the effect of the amount of reverberation in rooms as well as the angular separation between the target speech and noise sources, both of which are known to have a significant effect on speech intelligibility in real (i.e. non-virtual) acoustic environment. The experimental results suggest that the intelligibility of speech masked by pink noise was significantly reduced under reverberant acoustical environments reproduced by the Ambisonics-based sound reproduction system compared to the baseline anechoic environment. However, only marginal differences were observed between the acoustical environments with different reverberation time. The effect of spatial release from masking was also observed under the reproduced acoustic environments and showed some correlation with the accuracy of source localisation realised by the sound reproduction system.

English and Japanese listeners' identification of English consonants in (1) reverberant and (2) multispeaker babble noise plus reverberant listening environments showed that English listeners always outperformed Japanese listeners.Positive correlations were found between Japanese listeners' identification rates and TOEIC? scores and length of residence in English-speaking countries but not the age of onset of learning English.English and Japanese listeners misperceived different consonants in different listening environments. Moreover, misperception patterns of Japanese listeners with high proficiency resembled those with lower proficiency in demanding listening environments. Perceiving non-native sounds in adverse listening environments is challenging, even for proficient learners. An identification experiment in quiet, three reverberant (RT?=?0.78?s, 1.12?s, 1.43?s) and multispeaker babble?+?reverberant environments was carried out to investigate the relation of listening environments and non-native language proficiency. This research aims to elucidate (1) Japanese and English listeners' identification of intervocalic English consonants in quiet and adverse listening environments, and (2) the correlation of identification rates with the Japanese listeners' TOEIC? scores, age of onset of English acquisition and length of residence in English-speaking countries. Results showed (1) English listeners achieved significantly higher overall identification rates compared to Japanese listeners on the subset of 11 consonants /f ? ? l ? s ? ? ? v z/ that are often difficult for Japanese to accurately identify, and (2) positive correlations between identification rates and English proficiency measured by means of TOEIC? scores and LOR. Analysis of misperception patterns revealed that an increased amount of background disturbance led proficient listeners' misperception patterns to resemble those of the lower proficiency listeners, as in the example of native listeners misperceiving /g/ as /?/ in RT?=?1.12?s and highly proficient Japanese misperceiving /g/ as /?/, /?/, and /l/, and lower group as /?/ and /l/. The degradation of identification accuracy as background disturbance increased shed light on how one's L1 and L2 proficiency influence speech perception.

Previous research has revealed that Japanese native speakers are highly likely to both perceive and produce epenthetic vowels between consonants. The goal of the present study is to investigate the influence of English learning backgrounds in the perception and production of consonant clusters by Japanese native speakers. In Experiment 1, a forced-choice AXB task to identify VC(u)CV is assigned to 17 highly fluent Japanese-English bilinguals and 22 Japanese monolinguals. Results show that monolinguals made significantly more errors than bilinguals. In Experiment 2, the influence of English proficiency on the production of consonant clusters, and the effect of consonant voicing on vowel epenthesis are investigated. The epenthetic vowels are acoustically analyzed and categorized into three degrees: full, partial and no epenthesis. The voicing combinations of the consonant clusters are C[+voice]-C[+voice], C[−voice]-C[+voice], and C[−voice]-C[−voice]. Results show that monolinguals inserted more epenthetic vowels than bilinguals, and that the influence of consonant voicing was stronger in monolinguals than bilinguals. Furthermore, monolinguals’ epenthetic vowels between C[−voice]-C[+voice] and C[−voice]-C[−voice] tended to become devoiced than bilinguals. This result suggests a stronger L1 influence on monolinguals. The results of the two experiments thus suggest that the English proficiency influences the perception and production of consonant clusters.

Past research has repeatedly shown that perceiving speech in non-laboratory environments is challenging for both native and non-native listeners, even if they are able to perform well in laboratory (quiet) environment. However, whether the challenge of non-native listeners’ perception of non-native sounds in noise can be overcome with training has not been fully investigated. The present study reports preliminary analysis of training Japanese learners of English, focusing on the identification of English voiceless fricatives and approximants in multispeaker babble noise, as Japanese learners of English are well-known for having difficulty in accurate perception of such sounds (e.g., Lambacher et al., 2001; Masuda 2016 among others), especially in noisy listening environments. The experiment consists of three sessions: 1) pre-test, 2) training sessions in noise, and 3) post-test. Identification rates of 1) pre- and 3) post-tests will be compared to investigate the effect of 2) training in noise. The effect...