Chapters authored
Neurophysiological Correlate of Binaural Auditory Filter Bandwidth and Localization Performance Studied by Auditory Evoked Fields
Part of the book: Advances in Sound Localization
Effects of Platform Screen Doors on Sound Fields in Underground Stations
This chapter investigates the acoustic effects of platform screen doors (PSDs) in underground stations using computer simulation and scale model testing. The dimensions of underground stations with island and side platforms were determined based on a field survey. Ray-tracing-based computer models and 1/25 scaled-down physical models of these underground stations were used to simulate their sound field characteristics. In the experiments, five types of PSDs were tested: mobile closed full-height (MCFH), mobile open full-height (MOFH), mobile half-height (MHH), fixed half-height (FHH) and fixed barrier (FB) doors. Four acoustic parameters, namely, speech intelligibility, sound pressure level, reverberation time and the inter-aural cross-correlation coefficient were used to understand the sound field characteristics from the sound source of public address announcements. It was found that speech intelligibility and the sound pressure level were increased by most types of PSDs apart from the MCFH. The MOFH showed the highest levels of speech intelligibility and spatial diffusivity. In addition, the noise reduction effects of PSDs for train noise were discussed. PSDs on side platforms showed higher noise reduction performances than PSDs on island platforms. The specific noise reduction levels for the MOFH type were 4.3 dB on island platforms and 5.0 dB on side platforms.
Part of the book: Advances in Noise Analysis, Mitigation and Control
Psychophysiological Evidence of an Autocorrelation Mechanism in the Human Auditory System
This article details a model for evaluations of sound quality in the human auditory system. The model includes an autocorrelation function (ACF) mechanism. Thus, we conducted physiological and psychological experiments to search for evidence of the ACF mechanism in the human auditory system. To evaluate physiological responses related to the peak amplitude of the ACF of an auditory signal, which represents the degree of temporal regularity of the sound, we used magnetoencephalography (MEG) to record auditory evoked fields (AEFs). To evaluate psychological responses related to the envelope of the ACF of an auditory signal, which is a measure of the repetitive features of an auditory signal, we examined perceptions of loudness and annoyance. The results of the MEG experiments showed that the amplitude of the N1m, which is found above the left and right temporal lobes around 100 ms after stimulus onset, was a function of the peak amplitude and its delay time or the degree of envelope decay of the ACF. The results of the psychological experiments indicated that loudness and annoyance increased for sounds with envelope decay of the ACF in a certain range. These results suggest that an autocorrelation mechanism exists in the human auditory system.
Part of the book: Advances in Clinical Audiology