Proceedings of the EAA Spatial Audio Signal Processing symposium: SASP 2019

International audienc

Stress System Dynamics during “Life As It Is Lived”: An Integrative Single-Case Study on a Healthy Woman

Little is known about the dynamic characteristics of stress system activity during “life as it is lived”. Using as representative a study design as possible, this investigation sought to gain insights into this area. A healthy 25-year-old woman collected her entire urine over a period of 63 days in 12-h intervals (126 measurements) to determine cortisol and neopterin (immune activation marker) levels. In addition, she filled out questionnaires on emotional state and daily routine in 12-h intervals, and was interviewed weekly to identify emotionally negative and positive everyday incidents. Adjusted cross-correlational analyses revealed that stressful incidents were associated with cyclic response patterns in both urinary cortisol and urinary neopterin concentrations. Urinary cortisol levels first decreased 12–24 h after stressful incidents occurred (lag 1: −.178; p = 0.048) and then increased a total of 72–84 h later (lag 6: +.224; p = 0.013). Urinary neopterin levels first increased 0–12 h before the occurrence of stressful incidents (−lag 1: +.185; p = 0.040) and then decreased a total of 48–60 h following such stressors (lag 4: −.181; p = 0.044). Decreases in urinary neopterin levels were also found 24–36 and 48–60 h after increases in pensiveness (lag 2: −.215; p = 0.017) and depressiveness (lag 4: −.221; p = 0.014), respectively. Findings on emotionally positive incidents sharply contrasted with those dealing with negative experiences. Positive incidents were followed first by urinary cortisol concentration increases within 12 h (lag 0: +.290; p = 0.001) and then by decreases after a total of 60–72 h (lag 5: −.186; p = 0.039). Urinary neopterin levels first decreased 12–24 h before positive incidents occurred (−lag 2: −.233; p = 0.010) and then increased a total of 12–24 h following these incidents (lag 1: +.222; p = 0.014). As with previous investigations on patients with systemic lupus erythematosus (SLE), this study showed that stress system response can be considerably longer and more complex and differentiated than findings from conventional group studies have suggested. Further integrative single-case studies will need to be conducted in order to draw firm conclusions about stress system dynamics under real-life conditions

A comparative study of interaural time delay estimation methods

cote interne IRCAM: Katz14aNone / NoneNational audienceThe Interaural Time Delay (ITD) is an important binaural cue for sound source localization. Calculations of ITD values are obtained either from measured time domain Head-Related Impulse Responses (HRIRs) or from their frequency transform Head-Related Transfer Functions (HRTFs). Numerous methods exist in current literature, based on a variety of definitions and assumptions of the nature of the ITD as an acoustic cue. This work presents a thorough comparative study of the degree of variability between some of the most common methods for calculating the ITD from measured data. Thirty-two different calculations or variations are compared for positions on the horizontal plane for the HRTF measured on both a KEMAR mannequin and a rigid sphere. Specifically, the spatial variations of the methods are investigated. Included is a discussion of the primary potential causes of these differences, such as the existence of multiple peaks in the HRIR of the contra-lateral ear for azimuths near the inter-aural axis due to multipath propagation and head/pinnae shadowing

Reconstructing sound source directivity in virtual acoustic environments

cote interne IRCAM: Noisternig09aNone / NoneNational audienceReconstructing sound source directivity in virtual acoustic environment

Real-time auralization system based on beam-tracing and mixed-order Ambisonics

cote interne IRCAM: Noisternig08bNone / NoneNational audienceAuralization, the final step in computational room acoustic simulations, aims to make audible the acoustics of complex virtual architectural spaces in a realistic and accurate manner. This paper presents a novel real-time auralization system comprising a geometry engine, a beam-tracer, and an audio renderer. The computation of early reflection paths is based on an efficient beam-tracing algorithm capable of real-time detection of specular reflection paths in a static geometry with one or several moving listener(s). For simpler rooms, the real-time performance is maintained even with dynamic geometries and sources. Results of the beam-tracer, sent to the audio renderer, consist of visible reflection paths and their accumulated material attenuation. From this geometrical and acoustical data, listener position-related 3D room impulse responses are generated applying a higher-order virtual Ambisonics approach. Final rendering of the binaural room impulse response (BRIR) is made taking into account the listener's head-orientation. As higher order reflections are more diffuse in nature, they may be encoded using lower Ambisonic orders, thereby reducing computational load. The environment combines high quality audio with visual rendering realized using the open source platforms Pure Data and VirChor respectively. This auralization framework provides direct audio-visual feedback in real-time for VR environments

Scale Model Auralization for Art, Science, and Music: The Stupaphonic Experiment

cote interne IRCAM: Katz14bNone / NoneNational audienceThe use of acoustical scale models has been replaced for the most part by computational models and numerical simulations for room acoustic studies as well as artificial reverberation units. There remains however a number of acoustical phenomena which are difficult to address with computer simulations, such as coupled volumes, diffraction, and complex scattering, due to the computational complexity and/or calculation time necessary for addressing such acoustical wave phenomena on the scale of room acoustical problems, even small rooms. This paper presents a pilot study of a rather unique artistic architectural structure consisting of a self-supporting construction composed of small stacked linear elements. Acoustically, the structure combines modal behavior, concave forms, and very regular scattering patterns. An example scale model has been constructed and studied in order to separate different construction features and their associated acoustics effects. In an attempt to explore the interest of the specific acoustic for musical performance, a computational platform was created to utilize the scale model as a physical convolution reverberation unit for musical performance

Framework for Real-Time Auralization in Architectural Acoustics

cote interne IRCAM: Noisternig08aNone / NoneNational audienceAuralization is the process of making audible the acoustics of complex virtual architectural spaces in a realistic and accurate manner. This paper presents a novel real-time auralization software environment comprising a room acoustic modeler, a spatial renderer for auralization, and a visualization and scene graph unit for interactivity. The computation of early reflection paths within the geometric model is based on an efficient beam tracing algorithm capable of real-time detection of specular reflection paths in a static geometry with one or several moving listener(s). For “simple" rooms, the real-time performance is maintained even with dynamic geometries and sources. Results of the room acoustic model consisting of visible reflection paths and their accumulated material attenuation are sent to the audio renderer. From this geometrical and acoustical data, listener position-relative 3D room impulse responses are generated using a hierarchical-order Ambisonics approach. Finally, the spatialized audio output is presented to the listener via multiple loudspeakers or binaurally rendered over headphones. As higher order reflections are more diffuse in nature, they are encoded using lower Ambisonic orders, thereby reducing computational load. The environment combines high quality audio with visual rendering realized using the open source platforms Pure Data and VirChor respectively. This open source auralization framework provides direct audio-visual interaction in real-time and is suitable for VR environments

Implementation of real-time room auralization using a surrounding loudspeaker array

cote interne IRCAM: Okamoto09aNone / NoneNational audienceReal-time auralization systems have been developed for room acoustic simulations. For high quality spatial rendering, many of these systems have used binaurual rendering. This paper presents the implementation of a real-time room acoustics auralization system using an array of 157 loudspeakers. The room acoustic model uses a combination of an iterative image-source model and feedback delay networks to create the reflections and reverberation. Higher-order Ambisonics (HOA) is used to generate spatial room impulse responses. The speaker array uses a density grid of 50 cm and covers the walls and ceiling of a treated listening room. A distributed network system has been used to create the auralization. All software components of this system are Open-Source. In this paper, we introduce this system and discuss about the synchronous estumation of 157 audio signals

Unified link layer security design for IP encapsulation using unidirectional lightweight encapsulation over satellites

There is growing interest in providing multimedia and broadband access over satellites. However there are several technical challenges need to be addressed. One challenge is security in terms of understanding threats and providing an effective security system. Also this paper presents a ULE security solution using ULE mandatory extension headers. The design issues and choices are discussed. The detailed security header format is described together with processing sequence in both transmitter and receiver sides

Improving sound field reproduction based on higher-order ambisonics in a small room with a 157-loudspeaker array

cote interne IRCAM: Okamoto10aNone / NoneNational audienceThis article presents a case study of higher-order Ambisonics (HOA) for real-time sound field reproduction in a small room with a 157-loudspeaker array. It addresses a number of specific questions and practical issues on the system design and implementation, such as the reproduction room's acoustic, loudspeaker positioning and radiation patterns, distributed computing and audio channel synchronization, and in more general the achievable accuracy of sound field reproduction. In the current configuration of the system Ambisonics up to order n = 6 is applied and the decoders are rendered in parallel on a cluster of four computers. For this reason, synchronization and communication between the different computers becomes a challenging task for achieving a good system performance. The overall system latency and the inter-channel synchronicity have been measured using time-stretched pulse (TSP) signals. The measurement results have shown a maximum (unsigned) latency of 51 samples, which corresponds to t = 1.1 ms. It is obvious that the acoustic of the reproduction room has a strong effect on the accuracy of the Ambisonics sound field reproduction. To achieve semi-anechoic conditions sound absorption materials have been installed in the room. Finally, spatial filters have been applied to each individual loudspeaker to correct for different orientations with reference to the sweet spot. These filters have been derived from radiation pattern measurements in an anechoic chamber