Journal articles: 'First-order ambisonics'

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McKenzie, Thomas, Damian Murphy, and Gavin Kearney. "Interaural Level Difference Optimization of Binaural Ambisonic Rendering." Applied Sciences 9, no. 6 (March 23, 2019): 1226. http://dx.doi.org/10.3390/app9061226.

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Ambisonics is a spatial audio technique appropriate for dynamic binaural rendering due to its sound field rotation and transformation capabilities, which has made it popular for virtual reality applications. An issue with low-order Ambisonics is that interaural level differences (ILDs) are often reproduced with lower values when compared to head-related impulse responses (HRIRs), which reduces lateralization and spaciousness. This paper introduces a method of Ambisonic ILD Optimization (AIO), a pre-processing technique to bring the ILDs produced by virtual loudspeaker binaural Ambisonic rendering closer to those of HRIRs. AIO is evaluated objectively for Ambisonic orders up to fifth order versus a reference dataset of HRIRs for all locations on the sphere via estimated ILD and spectral difference, and perceptually through listening tests using both simple and complex scenes. Results conclude AIO produces an overall improvement for all tested orders of Ambisonics, though the benefits are greatest at first and second order.

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Zaunschirm, Markus, Matthias Frank, and Franz Zotter. "Binaural Rendering with Measured Room Responses: First-Order Ambisonic Microphone vs. Dummy Head." Applied Sciences 10, no. 5 (February 29, 2020): 1631. http://dx.doi.org/10.3390/app10051631.

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To improve the limited degree of immersion of static binaural rendering for headphones, an increased measurement effort to obtain multiple-orientation binaural room impulse responses (MOBRIRs) is reasonable and enables dynamic variable-orientation rendering. We investigate the perceptual characteristics of dynamic rendering from MOBRIRs and test for the required angular resolution. Our first listening experiment shows that a resolution between 15 ∘ and 30 ∘ is sufficient to accomplish binaural rendering of high quality, regarding timbre, spatial mapping, and continuity. A more versatile alternative considers the separation of the room-dependent (RIR) from the listener-dependent head-related (HRIR) parts, and an efficient implementation thereof involves the measurement of a first-order Ambisonic RIR (ARIR) with a tetrahedral microphone. A resolution-enhanced ARIR can be obtained by an Ambisonic spatial decomposition method (ASDM) utilizing instantaneous direction of arrival estimation. ASDM permits dynamic rendering in higher-order Ambisonics, with the flexibility to render either using dummy-head or individualized HRIRs. Our comparative second listening experiment shows that 5th-order ASDM outperforms the MOBRIR rendering with resolutions coarser than 30 ∘ for all tested perceptual aspects. Both listening experiments are based on BRIRs and ARIRs measured in a studio environment.

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Zaunschirm, Markus, Franck Zagala, and Franz Zotter. "Auralization of High-Order Directional Sources from First-Order RIR Measurements." Applied Sciences 10, no. 11 (May 28, 2020): 3747. http://dx.doi.org/10.3390/app10113747.

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Can auralization of a highly directional source in a room succeed if it employs a room impulse response (RIR) measurement or simulation relying on a first-order directional source, only? This contribution presents model and evaluation of a source-and-receiver-directional Ambisonics RIR capture and processing approach (SRD ARIR) based on a small set of responses from a first-order source to a first-order receiver. To enhance the directional resolution, we extend the Ambisonic spatial decomposition method (ASDM) to upscale the first-order resolution of both source and receiver to higher orders. To evaluate the method, a listening experiment was conducted based on first-order SRD-ARIR measurements, into which the higher-order directivity of icosahedral loudspeaker’s (IKO) was inserted as directional source of well-studied perceptual effects. The results show how the proposed method performs and compares to alternative rendering methods based on measurements taken in the same acoustic environment, e.g., multiple-orientation binaural room impulse responses (MOBRIRs) from the physical IKO to the KU-100 dummy head, or higher-order SRD ARIRs from IKO to em32 Eigenmike. For optimal externalization, our experiments exploit the benefits of virtual reality, using a highly realistic visualization on head-mounted-display, and a user interface to report localization by placing interactive visual objects in the virtual space.

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Hui, C. T. Justine, Yusuke Hioka, Catherine I. Watson, and Hinako Masuda. "Spatial release from masking in varying spatial acoustic under higher order ambisonic-based sound reproduction system." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 4 (August 1, 2021): 2476–85. http://dx.doi.org/10.3397/in-2021-2148.

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A previous study found that spatial release from masking (SRM) could be observed under virtual reverberant environments using a first order Ambisonic-based sound reproduction system, however, poor localisation accuracy made it difficult to examine effect of varying reverberation time on SRM. The present study follows on using higher order Ambisonics (HOA) to examine how benefits from SRM vary in different spatial acoustics. Subjective speech intelligibility was measured where four room acoustics:reverberation time (RT)= 0.7 s (clarity (C50)= 16 dB, 7 dB); RT= 1.8 s (C50= 8 dB, 2 dB) were simulated via a third order Ambisonic system with a 16 channel spherical loudspeaker array. The masker was played from 8 azimuthal angles (0, +-45, +-90, +-135, 180 degrees) while the target speech was played from 0 degree. The listeners are deemed to benefit from SRM if their intelligibility scores were higher when the masker comes from a different angle than that of the target. We found while listeners could benefit from SRM at C50 = 16 dB and 8 dB, the benefit starts to diminish at C50 = 7 dB, and listeners could no longer benefit from SRM at C50 = 2 dB.

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Bertet, Stéphanie, Jérôme Daniel, Etienne Parizet, and Olivier Warusfel. "Investigation on Localisation Accuracy for First and Higher Order Ambisonics Reproduced Sound Sources." Acta Acustica united with Acustica 99, no. 4 (July 1, 2013): 642–57. http://dx.doi.org/10.3813/aaa.918643.

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Oberman, Tin, Kristian Jambrošić, Marko Horvat, and Bojana Bojanić Obad Šćitaroci. "Using Virtual Soundwalk Approach for Assessing Sound Art Soundscape Interventions in Public Spaces." Applied Sciences 10, no. 6 (March 20, 2020): 2102. http://dx.doi.org/10.3390/app10062102.

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This paper discusses the soundscape assessment approaches to soundscape interventions with musical features introduced to public spaces as permanent sound art, with a focus on the ISO 12913 series, Method A for data collection applied in a laboratory study. Three soundscape interventions in three cities are investigated. The virtual soundwalk is used to combine the benefits of the on-site and laboratory settings. Two measurement points per location were recorded—one at a position where the intervention was clearly perceptible, the other further away to serve as a baseline condition. The participants (N = 44) were exposed to acoustic environments (N = 6) recorded using the first-order Ambisonics microphone on-site and then reproduced via the second-order Ambisonics system in laboratory. A series of rank-based Kruskal–Wallis tests were performed on the results of the subjective responses. Results revealed a statistically significant positive effect on soundscape at two locations, and limitations related to sound source identification due to cultural factors and geometrical configuration of the public space at one location.

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Narbutt, Miroslaw, Jan Skoglund, Andrew Allen, Michael Chinen, Dan Barry, and Andrew Hines. "AMBIQUAL: Towards a Quality Metric for Headphone Rendered Compressed Ambisonic Spatial Audio." Applied Sciences 10, no. 9 (May 3, 2020): 3188. http://dx.doi.org/10.3390/app10093188.

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Spatial audio is essential for creating a sense of immersion in virtual environments. Efficient encoding methods are required to deliver spatial audio over networks without compromising Quality of Service (QoS). Streaming service providers such as YouTube typically transcode content into various bit rates and need a perceptually relevant audio quality metric to monitor users’ perceived quality and spatial localization accuracy. The aim of the paper is two-fold. First, it is to investigate the effect of Opus codec compression on the quality of spatial audio as perceived by listeners using subjective listening tests. Secondly, it is to introduce AMBIQUAL, a full reference objective metric for spatial audio quality, which derives both listening quality and localization accuracy metrics directly from the B-format Ambisonic audio. We compare AMBIQUAL quality predictions with subjective quality assessments across a variety of audio samples which have been compressed using the Opus 1.2 codec at various bit rates. Listening quality and localization accuracy of first and third-order Ambisonics were evaluated. Several fixed and dynamic audio sources (single and multiple) were used to evaluate localization accuracy. Results show good correlation regarding listening quality and localization accuracy between objective quality scores using AMBIQUAL and subjective scores obtained during listening tests.

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Bertet, Stephanie, Jérôme Daniel, Etienne Parizet, and Olivier Warusfel. "Investigation on the restitution system influence over perceived Higher Order Ambisonics sound field: a subjective evaluation involving from first to fourth order systems." Journal of the Acoustical Society of America 123, no. 5 (May 2008): 3936. http://dx.doi.org/10.1121/1.2936007.

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Carpentier, Thibaut, Natasha Barrett, Rama Gottfried, and Markus Noisternig. "Holophonic Sound in IRCAM's Concert Hall: Technological and Aesthetic Practices." Computer Music Journal 40, no. 4 (December 2016): 14–34. http://dx.doi.org/10.1162/comj_a_00383.

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This article presents a report on technological and aesthetic practices in the variable-acoustics performance hall, Espace de Projection, at the Institut de Recherche et Coordination Acoustique/Musique. The hall is surrounded by a 350-loudspeaker array for sound-field reproduction using holophonic approaches such as wave-field synthesis and higher-order Ambisonics. First we present the design and implementation of the audio system and discuss the challenges of both hardware and software architectures. This is followed by a discussion of spatial composition techniques, aesthetic approaches, and methodologies for composing computer music for high-density loudspeaker arrays, explored through the paradigmatic examples of pieces produced by two artist-in-research residencies.

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Tarlao, Cynthia, Daniel Steele, and Catherine Guastavino. "Assessing the ecological validity of soundscape reproduction in different laboratory settings." PLOS ONE 17, no. 6 (June 27, 2022): e0270401. http://dx.doi.org/10.1371/journal.pone.0270401.

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The ever-growing body of soundscape research includes studies conducted both in everyday life environments and in laboratory settings. Yet, laboratory settings differ from in-situ and therefore may elicit different perceptions. The present study explores the ecological validity of soundscape reproduction in the laboratory using first-order Ambisonics and of different modes of questionnaire administration. Furthermore, it investigates the influence of the contextual factors of time of day, day of the week, and location on site on soundscape evaluations in situ and in the laboratory, based on the Swedish Soundscape Quality Protocol. We first tested measurement invariance between the computer-based and pen-and-paper administration of the soundscape questionnaire. We then investigated the influence of the above-mentioned contextual factors on soundscape evaluations, as well as the effect of stimuli selection in the laboratory. The analyses confirmed the underlying dimensions of proposed soundscape assessment questionnaires, confirmed metric invariance between computer and pen-and-paper, and revealed significant influences of time, day, and location on soundscape scales. This research represents a critical step in rigorously assessing soundscape evaluations in the laboratory and establishes solid evidence for the use of both in situ and laboratory soundscape studies.

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Zhao, Jiahong, Xiguang Zheng, Christian Ritz, and Daeyoung Jang. "Interpolating the Directional Room Impulse Response for Dynamic Spatial Audio Reproduction." Applied Sciences 12, no. 4 (February 16, 2022): 2061. http://dx.doi.org/10.3390/app12042061.

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Virtual reality (VR) is increasingly important for exploring the real world, which has partially moved to virtual workplaces. In order to create immersive presence in a simulated scene for humans, VR needs to reproduce spatial audio that describes three-dimensional acoustic characteristics in the counterpart physical environment. When the user moves, this reproduction should be dynamically updated, which provides practical challenges because the bandwidth for continuously transmitting audio and video scene data may be limited. This paper proposes an interpolation approach for dynamic spatial audio reproduction using acoustic characteristics of direction and reverberation at limited numbers of positions, which are represented using a first order Ambisonics encoding of the room impulse response (RIR), called the directional RIR (DRIR). We decompose two known DRIRs into reflection components, before interpolating early dominant components for DRIR synthesis and utilizing DRIR recordings for accuracy evaluation. Results indicate that the most accurate interpolation is obtained by the proposed method over two comparative approaches, particularly in a simulated small room where most direction of arrival estimation errors of early components are below five degrees. These findings suggest precise interpolated DRIRs with limited data using the proposed approach, which is vital for dynamic spatial audio reproduction for VR applications.

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Xu, Chunyang, Tin Oberman, Francesco Aletta, Huan Tong, and Jian Kang. "Ecological Validity of Immersive Virtual Reality (IVR) Techniques for the Perception of Urban Sound Environments." Acoustics 3, no. 1 (December 25, 2020): 11–24. http://dx.doi.org/10.3390/acoustics3010003.

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Immersive Virtual Reality (IVR) is a simulated technology used to deliver multisensory information to people under different environmental conditions. When IVR is generally applied in urban planning and soundscape research, it reveals attractive possibilities for the assessment of urban sound environments with higher immersion for human participation. In virtual sound environments, various topics and measures are designed to collect subjective responses from participants under simulated laboratory conditions. Soundscape or noise assessment studies during virtual experiences adopt an evaluation approach similar to in situ methods. This paper aims to review the approaches that are utilized to assess the ecological validity of IVR for the perception of urban sound environments and the necessary technologies during audio–visual reproduction to establish a dynamic IVR experience that ensures ecological validity. The review shows that, through the use of laboratory tests including subjective response surveys, cognitive performance tests and physiological responses, the ecological validity of IVR can be assessed for the perception of urban sound environments. The reproduction system with head-tracking functions synchronizing spatial audio and visual stimuli (e.g., head-mounted displays (HMDs) with first-order Ambisonics (FOA)-tracked binaural playback) represents the prevailing trend to achieve high ecological validity. These studies potentially contribute to the outcomes of a normalized evaluation framework for subjective soundscape and noise assessments in virtual environments.

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Tronchin, Lamberto, Francesca Merli, Massimiliano Manfren, and Benedetto Nastasi. "Validation and application of three-dimensional auralisation during concert hall renovation." Building Acoustics 27, no. 4 (June 5, 2020): 311–31. http://dx.doi.org/10.1177/1351010x20926791.

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During the renovation of auditoria and concert halls, the acoustic quality is normally evaluated from measurements of impulse responses. One possibility for evaluating the acoustic quality from the measurements (the simulations) consists of convolving anechoic music with the measured (or simulated) impulse responses. In this way, a psycho-acoustic test is achieved using a virtual sound field representation. The listening room ‘Arlecchino’ at the University of Bologna includes ambisonics (up to fifth order) and stereo-dipole playback for virtual reproduction of sound in rooms. In this article, the effectiveness of the listening room ‘Arlecchino’ is first analysed, comparing acoustic parameters obtained from binaural impulse responses measured in some opera houses (in Italy) and auditorium (in Japan) with those virtually measured after the virtual reconstruction obtained in the listening rooms. The similarity between real and virtual sound fields, has been evaluated by comparing different acoustic parameters calculated by real and virtual sound fields, in four halls in different configurations, by means of the stereo-dipole method. In the second part of the article, the listening room was used to analyse the variation in interaural cross-correlation measurements in rooms obtained considering different anechoic sound signals convolved with the binaural impulse responses, to quantify the variation of the interaural cross correlation with different motifs. For this purpose, two different musical instrument digital interface musical motifs, very different from each other for their music characteristics, have been considered. Moreover, for each musical motif, different sound characteristics (i.e. different musical instruments) were considered, to consider both the rhythmic and timbre aspect.

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Fazenda, Bruno M. "Misleading description of first and second order ambisonic systems." Building and Environment 179 (July 2020): 106981. http://dx.doi.org/10.1016/j.buildenv.2020.106981.

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Kearney, Gavin, Marcin Gorzel, Henry Rice, and Frank Boland. "Distance Perception in Interactive Virtual Acoustic Environments using First and Higher Order Ambisonic Sound Fields." Acta Acustica united with Acustica 98, no. 1 (January 1, 2012): 61–71. http://dx.doi.org/10.3813/aaa.918492.

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Sampedro Llopis, Hermes, Finnur Pind, and Cheol-Ho Jeong. "With regard to the letter to the editor by Bruno M. Fazenda. “Misleading description of first and second order Ambisonic systems”." Building and Environment 183 (October 2020): 107074. http://dx.doi.org/10.1016/j.buildenv.2020.107074.

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Lübeck, Tim, Sebastià V. Amengual Garí, Paul Calamia, David Lou Alon, Jeffery Crukley, and Zamir Ben-Hur. "Perceptual evaluation of approaches for binaural reproduction of non-spherical microphone array signals." Frontiers in Signal Processing 2 (August 15, 2022). http://dx.doi.org/10.3389/frsip.2022.883696.

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Microphone arrays consisting of sensors mounted on the surface of a rigid, spherical scatterer are popular tools for the capture and binaural reproduction of spatial sound scenes. However, microphone arrays with a perfectly spherical body and uniformly distributed microphones are often impractical for the consumer sector, in which microphone arrays are generally mounted on mobile and wearable devices of arbitrary geometries. Therefore, the binaural reproduction of sound fields captured with arbitrarily shaped microphone arrays has become an important field of research. In this work, we present a comparison of methods for the binaural reproduction of sound fields captured with non-spherical microphone arrays. First, we evaluated equatorial microphone arrays (EMAs), where the microphones are distributed on an equatorial contour of a rigid, spherical 1. Second, we evaluated a microphone array with six microphones mounted on a pair of glasses. Using these two arrays, we conducted two listening experiments comparing four rendering methods based on acoustic scenes captured in different rooms2. The evaluation includes a microphone-based stereo approach (sAB stereo), a beamforming-based stereo approach (sXY stereo), beamforming-based binaural reproduction (BFBR), and BFBR with binaural signal matching (BSM). Additionally, the perceptual evaluation included binaural Ambisonics renderings, which were based on measurements with spherical microphone arrays. In the EMA experiment we included a fourth-order Ambisonics rendering, while in the glasses array experiment we included a second-order Ambisonics rendering. In both listening experiments in which participants compared all approaches with a dummy head recording we applied non-head-tracked binaural synthesis, with sound sources only in the horizontal plane. The perceived differences were rated separately for the attributes timbre and spaciousness. Results suggest that most approaches perform similarly to the Ambisonics rendering. Overall, BSM, and microphone-based stereo were rated the best for EMAs, and BFBR and microphone-based stereo for the glasses array.

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Journal articles on the topic 'First-order ambisonics'

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