Real-time Microphone Array Processing for Sound-field Analysis and Perceptually Motivated Reproduction

This thesis details real-time implementations of sound-field analysis and perceptually motivated reproduction methods for visualisation and auralisation purposes. For the former, various methods for visualising the relative distribution of sound energy from one point in space are investigated and contrasted; including a novel reformulation of the cross-pattern coherence (CroPaC) algorithm, which integrates a new side-lobe suppression technique. Whereas for auralisation applications, listening tests were conducted to compare ambisonics reproduction with a novel headphone formulation of the directional audio coding (DirAC) method. The results indicate that the side-lobe suppressed CroPaC method offers greater spatial selectivity in reverberant conditions compared with other popular approaches, and that the new DirAC formulation yields higher perceived spatial accuracy when compared to the ambisonics method

Catholic schooling - a crisis revisited: a discussion of the key challenges confronting catholic schools today in the light of their history with particular reference to county Durham

Since the Second relief Act of 1791 the Catholic Church in England has placed exceptional reliance upon its schools to ensure the continuation of the faith. Throughout this period the Church hasdisplayed an extraordinary ability to adapt to, and equal, the external challenges that have consistently confronted its schooling policy. The various manoeuvres that it has been forced to make over the past 200 years provide testament to its resolute resistance to the potential loss of control of its schools; Without doubt the manner by which the Church has responded to past challenges has had a profound effect upon the nature of Catholic schooling today. Under close examination it becomes evident that many of the issues that currently dominate today's education debate have existed throughout the last two centuries and remarkably, while the Church has persevered with its schools policy, it has failed to determine any real schooling philosophy. The Church authorities at both national and local level have been so engrossed with meeting the demands of external threats that no clear vision or coherent policy has emerged and consequently much confusion remains as to the purpose and nature of Catholic schooling today. Despite all the sacrifices and advances made, recent government legislation bears the potential to provide the greatest challenge yet to the Church's policy while raising a serious questionmark against the very continuation of Catholic schooling. In this study I shall attempt to explore the key influences that have shaped the development of Catholic schooling and to examine today's crisis in an historical perspective as illuminated by the educational advances made by the Catholic community within Durham count

Parametric first-order ambisonic decoding for headphones utilising the cross-pattern coherence algorithm

International audienceRegarding the reproduction of recorded or synthesised spatial sound scenes, perhaps the most convenient and flexible approach is to employ the Ambisonics framework. The Ambisonics framework allows for linear and non-parametric storage, manipulation and reproduction of sound-fields, described using spherical harmonics up to a given order of expansion. Binaural Ambisonic reproduction can be realised by matching the spherical harmonic patterns to a set of binaural filters, in manner which is frequency-dependent, linear and time-invariant. However, the perceptual performance of this approach is largely dependent on the spatial resolution of the input format. When employing lower-order material as input, perceptual deficiencies may easily occur, such as poor localisation accuracy and colouration. This is especially problematic, as the vast majority of existing Ambisonic recordings are often made available as first-order only. The detrimental effects associated with lower-order Ambisonics reproduction have been well studied and documented. To improve upon the perceived spatial accuracy of the method, the simplest solution is to increase the spherical harmonic order at the recording stage. However, microphone arrays capable of capturing higher-order components, are generally much more expensive than first-order arrays; while more affordable options tend to offer higher-order components only at limited frequency ranges. Additionally, an increase in spherical harmonic order also requires an increase in the number of channels and storage, and in the case of transmission, more bandwidth is needed. Furthermore, it is important to note that this solution does not aid in the reproduction of existing lower-order recordings. It is for these reasons that this work focuses on alternative methods which improve the reproduction of first-order material for headphone playback. For the task of binaural sound-field reproduction, an alternative is to employ a parametric approach, which divides the sound-field decoding into analysis and synthesis stages. Unlike Ambisonic reproduction, which operates via a linear combination of the input signals, parametric approaches operate in the time-frequency domain and rely on the extraction of spatial parameters during their analysis stage. These spatial parameters are then utilised to conduct a more informed reproduction in the synthesis stage. Parametric methods are capable of reproducing sounds at a spatial resolution that far exceeds their linear and time-invariant counterparts, as they are not bounded by the resolution of the input format. For example, they can elect to directly convolve the analysed source signals with Head-Related Transfer Functions (HRTF), which correspond to their analysed directions. An infinite order of spherical harmonic components would be required to attain the same resolution with a binaural Ambisonic decoder. The most well-known and established parametric reproduction method is Directional Audio Coding (DirAC), which employs a sound-field model consisting of one plane-wave and one diffuseness estimate per time-frequency tile. These parameters are derived from the active-intensity vector, in the case of first-order input. More recent formulations allow for multiple plane-wave and diffuseness estimates via spatially-localised active-intensity vectors, using higher-order input. Another parametric method is High Angular Resolution plane-wave Expansion (HARPEX), which extracts two plane-waves per frequency and is first-order only. The Sparse-Recovery method extracts a number of plane-waves, which corresponds to up to half the number of input channels of arbitrary order. The COding and Multi-Parameterisation of Ambisonic Sound Scenes (COMPASS) method also extracts source components up to half the number of input channels, but employs an additional residual stream that encapsulates the remaining diffuse and ambient components in the scene. In this paper, a new binaural parametric decoder for first-order input is proposed. The method employs a sound-field model of one plane-wave and one diffuseness estimate per frequency, much like the DirAC model. However, the source component directions are identified via a plane-wave decomposition using a dense scanning grid and peak-finding, which is shown to be more robust than the active-intensity vector for multiple narrow-band sources. The source and ambient components per time-frequency tile are then segregated, and their relative energetic contributions are established, using the Cross-Pattern Coherence (CroPaC) spatial-filter. This approach is shown to be more robust than deriving this energy information from the active-intensity-based diffuseness estimates. A real-time audio plug-in implementation of the proposed approach is also described.A multiple-stimulus listening test was conducted to evaluate the perceived spatial accuracy and fidelity of the proposed method, alongside both first-order and third-order Ambisonics reproduction. The listening test results indicate that the proposed parametric decoder, using only first-order signals, is capable of delivering perceptual accuracy that matches or surpasses that of third-order ambisonics decoding

Interview of Leo D. Rudnytzky, Ph.D.

In this oral history, we cover Dr. Rudnytzky’s life from his early childhood in Ukraine and Eastern Europe to his formative years in the United States. He provides a detailed account of his time as an undergraduate student at La Salle University. The interview then spans his graduate studies and early years of teaching at La Salle, along with the differences between his time here, at Ivy League schools, and at foreign institutions. The subject discusses his involvement in various ethnic and religious groups and his impact on La Salle by way of symposiums, speakers, and programs, which he has brought into the University. The interview is riddled with references to the La Salle of the past. The subject regularly speaks of the changes that the University has undergone. His closing session focuses more intensively on those changes, and includes his reflections on his time as a teacher and his hopes for this university in the future

Parametric spatial audio effects based on the multi-directional decomposition of Ambisonic sound scenes

Decomposing a sound-field into its individual components and respective parameters can represent a convenient first-step towards offering the user an intuitive means of controlling spatial audio effects and sound-field modification tools. The majority of such tools available today, however, are instead limited to linear combinations of signals or employ a basic single-source parametric model. Therefore, the purpose of this paper is to present a parametric framework, which seeks to overcome these limitations by first dividing the sound-field into its multi-source and ambient components based on estimated spatial parameters. It is then demonstrated that by manipulating the spatial parameters prior to reproducing the scene, a number of sound-field modification and spatial audio effects may be realised; including: directional warping, listener translation, sound source tracking, spatial editing workflows and spatial side-chaining. Many of the effects described have also been implemented as real-time audio plug-ins, in order to demonstrate how a user may interact with such tools in practice.publishedVersionPeer reviewe

A spatial enhancement approach for binaural rendering of head-worn microphone arrays

This paper builds upon a recently proposed spatial enhancement approach, which has demonstrated im- provements in the perceived spatial accuracy of binaurally rendered signals using head-worn microphone arrays. The foundation of the approach is a parametric sound-field model, which assumes the existence of a single source and an isotropic diffuse component for each time-frequency index. The enhancement approach involves the post-processing of an initial estimate of the binaural signals, in order to obtain a refined esti- mate of binaural signals which more closely represent the inter-aural cues corresponding to the sound-field model. In this contribution, the enhancement approach has been implemented as an open-source framework, written in both the MATLAB and C programming languages, and as a real-time audio plug-in. The frame- work was also extended to offer direction-dependent gain control of sound sources relative to the listener, and a frequency-dependent control of the direct-to-diffuse balance, which are modifications that may find application within future augmented reality headsets and assistive hearing devices.publishedVersionNon peer reviewe

Parametric Ambisonic Encoding using a Microphone Array with a One-plus-Three Configuration

A parametric signal-dependent method is proposed for the task of encoding a studio omnidirectional microphone signal into the Ambisonics format. This is realised by affixing three additional sensors to the surface of the cylindrical microphone casing; representing a practical solution for imparting spatial audio recording capabilities onto an otherwise non-spatial audio compliant microphone. The one-plus-three configuration and parametric encoding method were evaluated through formal listening tests using simulated sound scenes and array recordings, given a binaural decoding workflow. The results indicate that, when compared to employing first-order signals obtained linearly using an open tetrahedral array, or third-order signals derived from a 19-sensor spherical array, the proposed system is able to produce perceptually closer renderings to those obtained using ideal third-order signals.publishedVersionPeer reviewe

Inviting pain? Pain, dualism and embodiment in narratives of self-injury

The role of pain in the practice of self-injury is not straightforward. Existing accounts suggest that self-injury does not cause 'physical' pain, however self-injury is also said to alleviate 'emotional' pain by inflicting 'physical' pain. This article explores these tensions using sociological theories regarding the socio-cultural and subjective nature of pain. Analysis derives from in-depth, life-story interviews carried out in the UK with people who had self-injured. Findings contribute to on-going debates within social science regarding the nature of pain. Participants' narratives about pain and self-injury both drew on and challenged dualistic models of embodiment. I suggest that self-injury offers a unique case on which to extend existing theoretical work, which has tended to focus on pain as an unwanted and uninvited entity. In contrast, accounts of self-injury can feature pain as a central aspect of the practice, voluntarily invited into lived experience. © 2013 The Authors. Sociology of Health & Illness © 2013 Foundation for the Sociology of Health & Illness/John Wiley & Sons Ltd

Expert consensus document: A 'diamond' approach to personalized treatment of angina.

In clinical guidelines, drugs for symptomatic angina are classified as being first choice (β-blockers, calcium-channel blockers, short-acting nitrates) or second choice (ivabradine, nicorandil, ranolazine, trimetazidine), with the recommendation to reserve second-choice medications for patients who have contraindications to first-choice agents, do not tolerate them, or remain symptomatic. No direct comparisons between first-choice and second-choice treatments have demonstrated the superiority of one group of drugs over the other. Meta-analyses show that all antianginal drugs have similar efficacy in reducing symptoms, but provide no evidence for improvement in survival. The newer, second-choice drugs have more evidence-based clinical data that are more contemporary than is available for traditional first-choice drugs. Considering some drugs, but not others, to be first choice is, therefore, difficult. Moreover, double or triple therapy is often needed to control angina. Patients with angina can have several comorbidities, and symptoms can result from various underlying pathophysiologies. Some agents, in addition to having antianginal effects, have properties that could be useful depending on the comorbidities present and the mechanisms of angina, but the guidelines do not provide recommendations on the optimal combinations of drugs. In this Consensus Statement, we propose an individualized approach to angina treatment, which takes into consideration the patient, their comorbidities, and the underlying mechanism of disease