3-D sound field reproduction with reverberation control on surround sound system by combining parametric and electro-dynamic loudspeakers

Recently, with the development of video technology, 3-D sound field reproduction systems that can provide a high presence have attracted attention. Conventional systems with electro-dynamic loudspeakers have a problem that the sound image lacks sharpness when constructing a narrow sound image. To solve this problem, we utilize a parametric array loudspeaker which has sharp directivity by the straightness of ultrasounds. Parametric array loudspeakers can produce sharper sound images due to the sharper directivity and lower reverberation compared with electro-dynamic loudspeakers. However, it is difficult to represent reverberation by parametric array loudspeakers. In this paper, we propose a method for 3-D sound field reproduction to achieve both the sharp images and reverberation presence by combing parametric array loudspeakers and electro-dynamic loudspeakers in surround sound system. In the proposed method, sharp sound images are rendered by parametric array loudspeakers and the reverberation presence is provided by electro-dynamic loudspeakers, emitting reverberation signals synthesized with a reverberation control filter. The reverberation control filter is adaptively designed to reproduce the reverberation time and the direct-to-reverberation ratio of the target sound field in other environments. The experimental results show that the proposed method can achieve the reproducing the sharp sound image with some reverberation presence.

Neural auditory contrast enhancement in humans

The perception of sensory events can be enhanced or suppressed by the surrounding spatial and temporal context in ways that facilitate the detection of novel objects and contribute to the perceptual constancy of those objects under variable conditions. In the auditory system, the phenomenon known as auditory enhancement reflects a general principle of contrast enhancement, in which a target sound embedded within a background sound becomes perceptually more salient if the background is presented first by itself. This effect is highly robust, producing an effective enhancement of the target of up to 25 dB (more than two orders of magnitude in intensity), depending on the task. Despite the importance of the effect, neural correlates of auditory contrast enhancement have yet to be identified in humans. Here, we used the auditory steady-state response to probe the neural representation of a target sound under conditions of enhancement. The probe was simultaneously modulated in amplitude with two modulation frequencies to distinguish cortical from subcortical responses. We found robust correlates for neural enhancement in the auditory cortical, but not subcortical, responses. Our findings provide empirical support for a previously unverified theory of auditory enhancement based on neural adaptation of inhibition and point to approaches for improving sensory prostheses for hearing loss, such as hearing aids and cochlear implants.

Harmonic Cancellation

This paper reviews the hypothesis of {\em harmonic cancellation}\ according to which an interfering sound is suppressed or canceled on the basis of its harmonicity (or periodicity in the time domain). It defines the concept, discusses theoretical arguments in its favor, and reviews experimental results that support it, or not. If correct, the hypothesis likely draws on time domain processing of temporally-accurate neural representations within the brainstem, as required also by the classic Equalization-Cancellation (EC) model of binaural unmasking. It predicts that a target sound corrupted by interference will be easier to hear if the interference is harmonic than inharmonic, all else being equal. This prediction is borne out in a number of behavioral studies, but not all. The paper reviews those results, with the aim to understand the inconsistencies and come up with a reliable conclusion for, or against, the hypothesis of harmonic cancellation within the auditory system.

Multiobjective optimisation of flight paths for noise level mitigation and sound quality improvement

The present work deals with the multiobjective, multidisciplinary optimisation of takeoff and approach operations of a commercial aircraft aimed at the mitigation of the impact of aviation noise on the population. The innovative approach used here couples the minimisation of the aircraft noise level at the certification points with the improvement of the sound quality. The latter objective represents the main novelty of the present work and is addressed using a spectral–matching approach to make the aircraft noise as close as possible to a target sound. The rationale underlying the research is the development of a community–oriented approach to the assessment airport operations in view of the complete redefinition of the future airport scenarios. Indeed, the air traffic growth, the rapid expansion of urban areas around airports, and the expected advent of urban air mobility, are transforming the aviation noise into a serious hazard to the sustainable development of society. The sound–quality–based objective imposes a comprehensive multidisciplinary approach also in the procedural optimisation, due to the detail required to estimate the noise spectrum composition. Two merit factors are minimised, specifically the EPNL at the noise certification points and the Lp –norm of the difference between the noise produced by the configuration under analysis and a target sound. The target sounds are obtained by using sound engineering techniques aimed at the sound quality improvement, on the basis of the results of the psychometric tests campaigns performed within the projects SEFA and COSMA. The minimisation is achieved adopting a global evolution method, and the results are presented in terms of approximated Pareto frontiers for a single–aisle aircraft in both takeoff and landing conditions.

Intonational Structure Influences Perception of Contrastive Vowel Length: The Case of Phrase-Final Lengthening in Tokyo Japanese

Recent research has proposed that listeners use prosodic information to guide their processing of phonemic contrasts. Given that prosodic organization of the speech signal systematically modulates durational patterns (e.g., accentual lengthening and phrase-final (PF) lengthening), listeners’ perception of durational contrasts has been argued to be influenced by prosodic factors. For example, given that sounds are generally lengthened preceding a prosodic boundary, listeners may adjust their perception of durational cues accordingly, effectively compensating for prosodically-driven temporal patterns. In the present study we present two experiments designed to test the importance of pitch-based cues to prosodic structure for listeners’ perception of contrastive vowel length (CVL) in Tokyo Japanese along these lines. We tested if, when a target sound is cued as being PF, listeners compensatorily adjust categorization of vowel duration, in accordance with PF lengthening. Both experiments were a two-alternative forced choice task in which listeners categorized a vowel duration continuum as a phonemically short or long vowel. We manipulated only pitch surrounding the target sound in a carrier phrase to cue it as intonational phrase final, or accentual phrase medial. In Experiment 1 we tested perception of an accented target word, and in Experiment 2 we tested perception of an unaccented target word. In both experiments, we found that contextual changes in pitch influenced listeners’ perception of CVL, in accordance with their function as signaling intonational structure. Results therefore suggest that listeners use tonal information to compute prosodic structure and bring this to bear on their perception of durational contrasts in speech.

Looming cue sounds

Studies suggest a prioritization in the neural processing of looming sounds. A little explored issue is the relationship between this perceptual bias and the orienting and alerting auditory attention networks. The present study investigated the effect of a warning sound on the speed of response to a subsequent target sound (Experiment 1) and a possible influence of this type of cue sound on the auditory orientation of attention (Experiment 2). The results of the two experiments suggest a significant reduction in the reaction time for a subsequent target sound due to the previous presentation (500 ms) of a looming warning sound. There was no significant effect of the cue sound on auditory attention orientation.

The Impressionistic Study of English /tʃ/ and /ʃ/ in Initial Position by L2 Thai Learners

Although studies on English sound learning by L2 Thai learners have been widely examined, there have been no studies on the production of the English /tʃ/ and /ʃ/ sounds in the initial position by L2 Thai learners with consideration of vowel contexts, the experience of L2 learners and target sounds. The aim of this study is to examine the production of the English /tʃ/ and /ʃ/ sounds in the initial position while taking the aforementioned factors into account. The data was from 48 L2 Thai learners, and the subjects were divided into two groups of university students: English-majors and non-English-majors. The two target sounds: English /tʃ/ and /ʃ/ together with the Thai /tɕʰ/ sound were tested in 27 words (9 words for each target sound). The subjects produced the target sounds five times, and their production was transcribed by two British transcribers. The results showed that the subjects had high target-like production when producing /ʃ/ but low target-like production when producing /tʃ/. In finding the correlation between the factors and the target-like production, neither the vowel contexts nor the experience could account for the production. The only factor that relates to the production of English /tʃ/ and /ʃ/ was the target sounds, i.e. the number of the productions that was deemed non-target-like was significantly higher when the target sound was /tʃ/ than when it was /ʃ/. This suggests that the target sounds, rather than the L2 experience and the vowel contexts, play a significant role in L2 speech production.