Object-based audio reproduction and the audio scene description format

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The introduction of new techniques for audio reproduction such as HRTF-based technology, wave field synthesis and higher-order Ambisonics is accompanied by a paradigm shift from channel-based to object-based transmission and storage of spatial audio. Not only is the separate coding of source signal and source location more efficient considering the number of channels used for reproduction by large loudspeaker arrays, it also opens up new options for a user-controlled interactive sound field design. This article describes the need for a common exchange format for object-based audio scenes, reviews some existing formats with potential to meet some of the requirements and finally introduces a new format called Audio Scene Description Format (ASDF) and presents the SoundScape Renderer, an audio reproduction software which implements a draft version of the ASDF

Object-based audio reproduction and the audio scene description format

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The introduction of new techniques for audio reproduction such as HRTF-based technology, wave field synthesis and higher-order Ambisonics is accompanied by a paradigm shift from channel-based to object-based transmission and storage of spatial audio. Not only is the separate coding of source signal and source location more efficient considering the number of channels used for reproduction by large loudspeaker arrays, it also opens up new options for a user-controlled interactive sound field design. This article describes the need for a common exchange format for object-based audio scenes, reviews some existing formats with potential to meet some of the requirements and finally introduces a new format called Audio Scene Description Format (ASDF) and presents the SoundScape Renderer, an audio reproduction software which implements a draft version of the ASDF

Studying the perception of sound in space : granular sounds spatialized in a high-order ambisonics system

Space is an important aspect of music composition that received little emphasis in certain periods of the history of Western music. However, in the twentieth century, electroacoustic music reintroduced this element by utilizing the different spatialization methods available. In this article, we discuss the methodology of analysis and the results of a study of the perception of sound in space involving sounds generated by granular synthesis that were spatialized in a high-order ambisonics system performed at CIRRMT’s Immersive Presence Laboratory at McGill University. We investigated two hypotheses of sound perception in space: 1) the variation of the granular synthesis parameters produces differences in the morphology of sounds perceived in their time-varying spatial distribution; and 2) the presence of more morphological sound variations when higher orders of ambisonics are employed, in addition to the generation of sound fields with more depth. In order to verify these hypotheses, we employed a method of analysis based on graphical representations of data derived from audio descriptors, such as graphical curves, a graphic representation of volume and phase space graphics. As a result, we observed that when higher orders of ambisonics are employed, the listener perceives more variations in frequency and intensity in sound spatialization, in addition to a preponderance of the decorrelation effect. Such effect is related to the presence of more diffuse sound fields262CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP304431/2018-4; 429620/2018-72016/23433-

WFS and HOA: Simulations and evaluations of planar higher order ambisonic, wave field synthesis and surround hybrid algorithms for lateral spatial reproduction in theatre.

Wave Field Synthesis and Higher Order Ambisonics are both spatialisation techniques that could be applied to theatre sound design, but practicalities such as the number of loudspeakers and space required limit their use. Practical setups could consist of a planar array across the stage (for performer localisation) and surround speakers around the auditorium in different configurations (for ambience). This research simulates the use of extrapolated and truncated arrays, with HOA and WFS algorithms in order to create a panned frontal dominant system with potentially increased intelligibility due to source separation and spatial unmasking. Hybrid methods where WFS and ambisonics are used simultaneously will be evaluated to create a system for theatre that is both psychoacoustically sound, homogenous and practicable.N/

Proceedings of the Learning Workshop on Livelihoods Analysis. Long An, Vietnam 19-20 November 2002

Sustainable Aquaculture for Poverty Alleviation (SAPA) is a strategy under the overall national program for hunger eradication and poverty reduction. This reflects high attention by the Ministry of Fisheries (MOFI) to the poor. Since the strategy was initiated, several actions have been taken. Recently, conferences and meetings were conducted in Hanoi, Thai Nguyen and Quang Tri. Consequently we also have workshops on a regional basis, and today we are pleased to conduct a workshop in Long An on livelihoods analysis. Now at the Ministry, there are more than 340 projects in aquaculture to attack poverty. The launch of SAPA has been given a high priority among support agencies. Recently Mr Gill of the World Bank and the Ministry agreed that they would act to strengthen aquaculture for poverty reduction. So today with the support of the Long An People’s Committee, NACA and STREAM we have a workshop to strengthen learning about livelihoods analysis. (PDF has 61 pages.

非球形のアレイ形状を持つAmbisonicsの定式化

Tohoku University鈴木陽一課

Embedding Distance Information in Binaural Renderings of Far Field Recordings

Traditional representations of sound fields based on spherical harmonics expansions do not include the sound source distance information. As multipole expansions can accurately encode the distance of a sound source, they can be used for accurate sound field reproduction. The binaural reproduction of multipole encodings, though, requires head-related transfer functions (HRTFs) with distance information. However, the inclusion of distance information on available data sets of HRTFs, using acoustic propagators, requires demanding regularization techniques. We alternatively propose a method to embed distance information in the spherical harmonics encodings of compact microphone array recordings. We call this method the Distance Editing Binaural Ambisonics (DEBA). DEBA is applied to the synthesis of binaural signals of arbitrary distances using only far-field HRTFs. We evaluated DEBA by synthesizing HRTFs for nearby sources from various samplings of far-field ones. Comparisons with numerically calculated HRTFs yielded mean spectral distortion values below 6 dB, and mean normalized spherical correlation values above 0.97

A Measure Based on Beamforming Power for Evaluation of Sound Field Reproduction Performance

This paper proposes a measure to evaluate sound field reproduction systems with an array of loudspeakers. The spatially-averaged squared error of the sound pressure between the desired and the reproduced field, namely the spatial error, has been widely used, which has considerable problems in two conditions. First, in non-anechoic conditions, room reflections substantially deteriorate the spatial error, although these room reflections affect human localization to a lesser degree. Second, for 2.5-dimensional reproduction of spherical waves, the spatial error increases consistently due to the difference in the amplitude decay rate, whereas the degradation of human localization performance is limited. The measure proposed in this study is based on the beamforming powers of the desired and the reproduced fields. Simulation and experimental results show that the proposed measure is less sensitive to room reflections and the amplitude decay than the spatial error, which is likely to agree better with the human perception of source localization