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Summary: This study examines electroglottographic (EGG) recordings for 15 young and 14 old male speakers of New Zealand English. Analysis was performed on the sustained vowels /i:/ and /a:/ at three target levels for both pitch and loudness. Jitter was greater for older speakers, and the contact quotient (Qx) was significantly lower for older speakers. The greater jitter for older speakers indicates a decrease in the stability of the vocal production mechanism of the older speakers. The jitter is an acoustic measure, so to examine the stability at a physiological level, a perturbation measure of the Qx is developed and applied to the EGG recordings. The contact quotient perturbation (CQP) showed a significant increase for older speakers (1.55% and 3.54% for young and old, respectively), and this demonstrated more about the variability than the jitter data alone. When loudness is also considered, the Qx was significantly greater for louder vowels, whereas its perturbation was significantly lower for louder vowels. This relationship combined with the age effect, with the CQP for all three loudness levels being greater for the older speakers. The findings of this study will contribute to the development of vocal fold models that account for aging. [Copyright &y& Elsevier]

An alternative design of masker for real-time speech masking is proposed. Time-reversed speech, which is also adopted in the proposed design, has been commonly used for speech masking because of its efficient performance in making the target speech unintelligible using informational masking. However, previous studies revealed that a time-reversed speech causes more annoyance and cognitive distraction for the listeners. Meanwhile, although generating time-reversed speech from the target speech would help improve masking effectiveness, it would require real-time processing as the target speech would not be available beforehand. The proposed masker design utilises techniques known for minimising discontinuities in the waveform of synthesised speech in order to minimise annoyance and distraction to the listeners. The design also avoids processes that hinders real-time generation of the masker. Results of subjective listening tests reveal that the proposed design is able to compromise the level of annoyance and the masking effect. Only marginal improvement is observed in the level of distraction. Further attempt to mitigate annoyance of the proposed masker by adding artificial reverberation did not help as it also reduces the masking effect significantly. [ABSTRACT FROM AUTHOR]

• Six types of background noise were used as maskers: Pink, Babble, Time-reversed speech with randomly re-ordered frames (T-rev), T-rev with artificial reverberation (Trev + Reverb), Time-reversed speech using overlap-and-add (OLaW), and OLaW with artificial reverberation (OLaW + Reverb). • Some maskers showed clear differences in their effectiveness of masking speech towards native and non-native listeners. • Within the non-native listeners, higher proficiency did not result in lower masking effects in masked speech. • Maskers generated using randomly re-ordered frames (T-rev and T-rev + Reverb) had higher masking effects but were also rated as more annoying. • Considering the balance of tradeoff between intelligibility and annoyance, OLaW and OLaW + Reverb maskers appear to be the most effective maskers for both native and nonnative listeners out of the six maskers. Speech masking is a technique used for protecting speech confidentiality, which is realised by adding maskers to cover target speech. Numerous studies have demonstrated the native and non-native differences in perceiving masked speech, but few have compared the effect of masker types from the perspective of effectiveness of speech privacy and their annoyance levels. This paper reports on the result of an English word perception task by native and non-native listeners where six types of maskers, both speech-like and non-speech-like, are implemented, as well as the annoyance levels of each masker. Natives, non-natives residing in an English-speaking country, and non-natives residing in a non-English-speaking country were tasked to write down sentences when masking sound was present, and also to rate the annoyance levels of the maskers. Results showed that language background significantly affected the performance of unmasked speech, the difference between the two non-native listeners became minimal in the presence of maskers, and maskers annoyed the listener groups differently, calling for a discussion in the selection of a universally effective masker to increase speech privacy. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]