Measurements and analysis of cavitation in a pressure reducing valve during operation – a case study

This paper proposes a methodology and presents its practical application for evaluating whether a pressure reducing valve (PRV) is under cavitation during its operation in a water distribution system. The approach is based on collecting measurements over a 24-hour period such that high demand and low demand times are included. The ollected measurements allow evaluation of four indicators related to cavitation, namely the draulic cavitation index, noise generated by the valve, acoustic cavitation index and the spectra of the noise. These four indicators provide sufficient information for diagnosis of cavitation with high certainty

Listening in the mix: lead vocals robustly attract auditory attention in popular music

Listeners can attend to and track instruments or singing voices in complex musical mixtures, even though the acoustical energy of sounds from individual instruments may overlap in time and frequency. In popular music, lead vocals are often accompanied by sound mixtures from a variety of instruments, such as drums, bass, keyboards, and guitars. However, little is known about how the perceptual organization of such musical scenes is affected by selective attention, and which acoustic features play the most important role. To investigate these questions, we explored the role of auditory attention in a realistic musical scenario. We conducted three online experiments in which participants detected single cued instruments or voices in multi-track musical mixtures. Stimuli consisted of 2-s multi-track excerpts of popular music. In one condition, the target cue preceded the mixture, allowing listeners to selectively attend to the target. In another condition, the target was presented after the mixture, requiring a more “global” mode of listening. Performance differences between these two conditions were interpreted as effects of selective attention. In Experiment 1, results showed that detection performance was generally dependent on the target’s instrument category, but listeners were more accurate when the target was presented prior to the mixture rather than the opposite. Lead vocals appeared to be nearly unaffected by this change in presentation order and achieved the highest accuracy compared with the other instruments, which suggested a particular salience of vocal signals in musical mixtures. In Experiment 2, filtering was used to avoid potential spectral masking of target sounds. Although detection accuracy increased for all instruments, a similar pattern of results was observed regarding the instrument-specific differences between presentation orders. In Experiment 3, adjusting the sound level differences between the targets reduced the effect of presentation order, but did not affect the differences between instruments. While both acoustic manipulations facilitated the detection of targets, vocal signals remained particularly salient, which suggest that the manipulated features did not contribute to vocal salience. These findings demonstrate that lead vocals serve as robust attractor points of auditory attention regardless of the manipulation of low-level acoustical cues

Virtual reality exposure therapy for reducing social anxiety in stuttering: a randomized controlled pilot trial

We report on findings from the first randomized controlled pilot trial of virtual reality exposure therapy (VRET) developed specifically for reducing social anxiety associated with stuttering. People who stutter with heightened social anxiety were recruited from online adverts and randomly allocated to receive VRET (n = 13) or be put on a waitlist (n = 12). Treatment was delivered remotely using a smartphone-based VR headset. It consisted of three weekly sessions, each comprising both performative and interactive exposure exercises, and was guided by a virtual therapist. Multilevel model analyses failed to demonstrate the effectiveness of VRET at reducing social anxiety between pre- and post-treatment. We found similar results for fear of negative evaluation, negative thoughts associated with stuttering, and stuttering characteristics. However, VRET was associated with reduced social anxiety between post-treatment and one-month follow-up. These pilot findings suggest that our current VRET protocol may not be effective at reducing social anxiety amongst people who stutter, though might be capable of supporting longer-term change. Future VRET protocols targeting stuttering-related social anxiety should be explored with larger samples. The results from this pilot trial provide a solid basis for further design improvements and for future research to explore appropriate techniques for widening access to social anxiety treatments in stuttering

Training spatial hearing skills in virtual reality through a sound-reaching task

Sound localization is crucial for interacting with the surrounding world. This ability can be learned across time and improved by multisensory and motor cues. In the last decade, studying the contributions of multisensory and motor cues has been facilitated by the increased adoption of virtual reality (VR). In a recent study, sound localization had been trained through a task where the visual stimuli were rendered through a VR headset, and the auditory ones through a loudspeaker moved around by the experimenter. Physically reaching to sound sources reduced sound localization errors faster and to a greater extent if compared to naming sources’ positions. Interestingly, training efficacy extended also to hearing-impaired people. Yet, this approach is unfeasible for rehabilitation at home. Fullyvirtual approaches have been used to study spatial hearing learning processes, performing headphones-rendered acoustic simulations. In the present study, we investigate whether the effects of our reaching-based training can be observed when taking advantage of such simulations, showing that the improvement is comparable between the full-VR and blended VR conditions. This validates the use of training paradigms that are completely based on portable equipment and don’t require an external operator, opening new perspectives in the field of remote rehabilitation

Classifying non-individual head-related transfer functions with a computational auditory model: calibration and metrics

This study explores the use of a multi-feature Bayesian auditory sound localisation model to classify non-individual head-related transfer functions (HRTFs). Based on predicted sound localisation performance, these are grouped into ‘good’ and ‘bad’, and the ‘best’/‘worst’ is selected from each category. Firstly, we present a greedy algorithm for automated individual calibration of the model based on the individual sound localisation data. We then discuss data analysis of predicted directional localisation errors and present an algorithm for categorising the HRTFs based on the localisation error distributions within a limited range of directions in front of the listener. Finally, we discuss the validity of the classification algorithm when using averaged instead of individual model parameters. This analysis of auditory modelling results aims to provide a perceptual foundation for automated HRTF personalisation techniques for an improved experience of binaural spatial audio technologies

PlugSonic: a web- and mobile-based platform for binaural audio and sonic narratives

PlugSonic is a suite of web- and mobile-based applications for the curation and experience of binaural interactive soundscapes and sonic narratives. It was developed as part of the PLUGGY EU project (Pluggable Social Platform for Heritage Awareness and Participation) and consists of two main applications: PlugSonic Sample, to edit and apply audio effects, and PlugSonic Soundscape, to create and experience binaural soundscapes. The audio processing within PlugSonic is based on the Web Audio API and the 3D Tune-In Toolkit, while the exploration of soundscapes in a physical space is obtained using Apple's ARKit. In this paper we present the design choices, the user involvement processes and the implementation details. The main goal of PlugSonic is technology democratisation; PlugSonic users - whether institutions or citizens - are all given the instruments needed to create, process and experience 3D soundscapes and sonic narrative; without the need for specific devices, external tools (software and/or hardware), specialised knowledge or custom development. The evaluation, which was conducted with inexperienced users on three tasks - creation, curation and experience - demonstrates how PlugSonic is indeed a simple, effective, yet powerful tool

Assessing HRTF preprocessing methods for Ambisonics rendering through perceptual models

Binaural rendering of Ambisonics signals is a common way to reproduce spatial audio content. Processing Ambisonics signals at low spatial orders is desirable in order to reduce complexity, although it may degrade the perceived quality, in part due to the mismatch that occurs when a low-order Ambisonics signal is paired with a spatially dense head-related transfer function (HRTF). In order to alleviate this issue, the HRTF may be preprocessed so its spatial order is reduced. Several preprocessing methods have been proposed, but they have not been thoroughly compared yet. In this study, nine HRTF preprocessing methods were used to render anechoic binaural signals from Ambisonics representations of orders 1 to 44, and these were compared through perceptual hearing models in terms of localisation performance, externalisation and speech reception. This assessment was supported by numerical analyses of HRTF interpolation errors, interaural differences, perceptually-relevant spectral differences, and loudness stability. Models predicted that the binaural renderings’ accuracy increased with spatial order, as expected. A notable effect of the preprocessing method was observed: whereas all methods performed similarly at the highest spatial orders, some were considerably better at lower orders. A newly proposed method, BiMagLS, displayed the best performance overall and is recommended for the rendering of bilateral Ambisonics signals. The results, which were in line with previous literature, indirectly validate the perceptual models’ ability to predict listeners’ responses in a consistent and explicable manner

Design and evaluation of a web-and mobile-based binaural audio platform for cultural heritage

PlugSonic is a suite of web- and mobile-based applications for the curation and experience of 3D interactive soundscapes and sonic narratives in the cultural heritage context. It was developed as part of the PLUGGY EU project (Pluggable Social Platform for Heritage Awareness and Participation) and consists of two main applications: PlugSonic Sample, to edit and apply audio effects, and PlugSonic Soundscape, to create and experience 3D soundscapes for headphones playback. The audio processing within PlugSonic is based on the Web Audio API and the 3D Tune-In Toolkit, while the mobile exploration of soundscapes in a physical space is obtained using Apple’s ARKit. The main goal of PlugSonic is technology democratisation; PlugSonic users-whether cultural institutions or citizens-are all given the instruments needed to create, process and experience 3D soundscapes and sonic narratives; without the need for specific devices, external tools (software and/or hardware), specialised knowledge or custom development. The aims of this paper are to present the design and development choices, the user involvement processes as well as a final evaluation conducted with inexperienced users on three tasks (creation, curation and experience), demonstrating how PlugSonic is indeed a simple, effective, yet powerful tool

Towards Large Scale Evaluation of Novel Sonification Techniques for Non Visual Shape Exploration

© 2015 ACM.There are several situations in which a person with visual impairment or blindness needs to extract information from an image. Examples include everyday activities, like reading a map, as well as educational activities, like exercises to develop visuospatial skills. In this contribution we propose a set of 6 sonification techniques to recognize simple shapes on touchscreen devices. The effectiveness of these sonification techniques is evaluated though Invisible Puzzle, a mobile application that makes it possible to conduct non-supervised evaluation sessions. Invisible Puzzle adopts a gamification approach and is a preliminary step in the development of a complete game that will make it possible to conduct a large scale evaluation with hundreds or thousands of blind users. With Invisible Puzzle we conducted 131 tests with sighted subjects and 18 tests with subjects with blindness. All subjects involved in the process successfully completed the evaluation session, with high engagement, hence showing the effectiveness of the evaluation procedure. Results give interesting insights on the differences among the sonification techniques and, most importantly, show that, after a short training, subjects are able to identify many different shapes