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1

Localization of sound sources in binaural reproduction of first and third order ambisonics

Sagasti Amaia, Pietrzak Agnieszka Paula, Martin Ricardo, Eguinoa Rubén

Vibrations in Physical Systems

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2022

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Vol. 33, nr 2

art. no. 2022214

EN

The use of higher-order ambisonics in spatial sound recordings makes it possible to increase the accuracy of recording information about the direction from which the sound comes to the listener. However, with binaural ambisonic sound reproduction, the listener's ability to locate the sound source accurately may be limited. This paper presents a comparison of the listener's ability to locate a sound source during binaural listening to recordings made with first and third order ambisonic microphones. The analysis was carried out for two types of signal: pink noise and ringing sound. The analysis of localization errors depending on the ambisonics order, azimuth and elevation angles as well as the type of signal is presented. The obtained data indicate that in binaural reproduction of the ambisonic sound the localization errors in the azimuth plane were smaller for the third order ambisonics, compared to the first order. In the elevation plane both for first and third order the errors were significant.

2

Application of an ambisonic microphone for the measurements of room acoustic parameters

Jasiński Maciej, Żera Jan

Vibrations in Physical Systems

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2022

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Vol. 33, nr 3

art. no. 2022312

EN

The most commonly used measurement technique in room acoustics employs a single omnidirectional microphone for recording the room impulse response and further derivation of such acoustical parameters as T30, EDT, C50 or C80. Instead, ambisonic technology makes it possible to measure a spatial room impulse response. Ambisonics decomposes the signal from the spherical microphone array into spherical harmonics to shape the directivity. Ambisonics lets to go beyond basic acoustical parameters and allows to determine spatial features of a sound field at the measurement point. This study presents the comparison of fundamental acoustic parameters measured in the recording studio by an actual omnidirectional microphone and virtual omnidirectional microphones derieved from ambisonic microphones of the first and third order. The results show the usefulness of ambisonic technology in terms of assessing basic room parameters.

3

Influence of Loudspeaker Configurations and Orientations on Sound Localization

Yao Shu-Nung

Archives of Acoustics

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2022

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Vol. 47, No. 1

57--70

EN

As the virtual reality (VR) market is growing at a fast pace, numerous users and producers are emerging with the hope to navigate VR towards mainstream adoption. Although most solutions focus on providing high- resolution and high-quality videos, the acoustics in VR is as important as visual cues for maintaining consistency with the natural world. We therefore investigate one of the most important audio solutions for VR applications: ambisonics. Several VR producers such as Google, HTC, and Facebook support the ambisonic audio format. Binaural ambisonics builds a virtual loudspeaker array over a VR headset, providing immersive sound. The configuration of the virtual loudspeaker influences the listening perception, as has been widely discussed in the literature. However, few studies have investigated the influence of the orientation of the virtual loudspeaker array. That is, the same loudspeaker arrays with different orientations can produce different spatial effects. This paper introduces a VR audio technique with optimal design and proposes a dual-mode audio solution. Both an objective measurement and a subjective listening test show that the proposed solution effectively enhances spatial audio quality.

4

Eksternalizacja w binauralnej ambisonicznej auralizacji źródeł kierunkowych

Mróz B., Kostek B.

Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

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2018

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Nr 60

75--80

PL

W artykule przedstawiono najważniejsze składniki procesu skutecznego renderowania trójwymiarowego obrazu dźwiękowego za pomocą słuchawek. W tym celu badany jest stopień oddziaływania poszczególnych czynników wpływających na eksternalizację dźwięku: śledzenie położenia głowy (ang. head tracking), indywidualne funkcje przenoszenia głowy (HRTF – Head Related Transfer Function, odnoszące się do matematycznej funkcji propagacji dźwięku wokół głowy), model pomieszczenia, jak również tzw. efekt zgodności pomieszczenia oraz indywidualne wyrównywanie charakterystyki przenoszenia słuchawek. Uzyskane wyniki wskazują, że śledzenie głowy, a także indywidualne funkcje przenoszenia głowy mają kluczowe znaczenie dla wiernej reprodukcji dźwięku. Z przeprowadzonych badań wynika również, że efekt zgodności pomieszczenia i wyrównywanie charakterystyki przenoszenia słuchawek są znaczącymi elementami procesu auralizacji.

EN

The article presents the most important components of the process of effectively rendering a three-dimensional sound image using headphones. To this end, the impact of a set of factors affecting sound externalisation is examined: head tracking, individual head transfer functions (HRTF – Head Related Transfer Function, related to the mathematical function of sound propagation around the head), room model, as well as a so-called room divergence effect and individual headphone alignment. Furthermore, the directivity aspect of the sound source is discussed as a convenient way to control Direct-toReverberant ratio and thus provides a robust control of the auditory distance. The results obtained indicate that the tracking of the head position as well as the individual functions of the head transfer are crucial for faithful sound reproduction. The conducted research also shows that the effect of room compliance and headphone alignment prove to be significant factors throughout the auralisation process.

5

Stanowisko badawcze CIOP-PIB do badań percepcji dźwięku przestrzennego z zastosowaniem techniki ambisonicznej

Szczepański G., Morzyński L., Pleban D., Młyński R.

Bezpieczeństwo Pracy : nauka i praktyka

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2018

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nr 10

24-27

PL

W warunkach środowiska pracy sygnały akustyczne mogą być źródłem informacji wpływającej na bezpieczeństwo pracowników. Możliwości percepcji dźwięków, słyszenia kierunkowego czy też orientacji przestrzennej osób w środowisku pracy zależą od szeregu czynników, takich jak właściwości akustyczne pomieszczeń pracy, hałas i jego parametry, ubytki słuchu, stosowanie ochron słuchu czy protez słuchu. Badanie wpływu tych czynników na wymienione możliwości (percepcja, słyszenie kierunkowe, orientacja) wymaga zastosowania dźwięku przestrzennego i ma istotne znaczenie dla tworzenia bezpiecznych warunków pracy. W artykule przedstawiono podstawowe informacje na temat techniki ambisonicznej jako jednej z technik przetwarzania dźwięku przestrzennego. Scharakteryzowano wykonane w Centralnym Instytucie Ochrony Pracy – Państwowym Instytucie Badawczym stanowisko laboratoryjne umożliwiające prowadzenie (z wykorzystaniem techniki ambisonicznej) badań percepcji dźwięków, słyszenia kierunkowego i orientacji przestrzennej osób.

EN

Acoustic signals can be a source of information affecting workers’ safety in the working environment. Sound perception, directional hearing and spatial orientation of people in the working environment depend on a number of factors, such as acoustic properties of the work room, noise and its parameters, the use of hearing protection, hearing loss or the use of hearing aids. Learning about the impact of these factors on perception, directional hearing and orientation requires using spatial sound and is essential for creating safe working conditions. This article presents basic information about ambisonics, a technique of spatial sound processing, and a test stand developed at the Central Institute for Labour Protection - National Research Institute for research on sound perception, directional hearing and spatial orientation of people using ambisonics.

6

Providing Surround Sound with Loudspeakers: A Synopsis of Current Methods

Blauert J., Rabenstein R.

Archives of Acoustics

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2012

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Vol. 37, No. 1

5-18

EN

Available methods for room-related sound presentation are introduced and evaluated. A focus is put on the synthesis side rather than on complete transmission systems. Different methods are compared using common, though quite general criteria. The methods selected for comparison are: INTENSITY STEREOPHONY after Blumlein, vector-base amplitude panning (VBAP), 5.1-SURROUND and its discrete-channel derivatives, synthesis with spherical harmonics (AMBISONICS, HOA), synthesis based on the boundary method, namely, wave-field synthesis (WFS), and binaural-cue selection methods (e.g., DIRAC). While VBAP, 5.1-SURROUND and other discrete-channel-based methods show a number of practical advantages, they do, in the end, not aim at authentic sound-field reproduction. The so-called holophonic methods that do so, particularly, HOA and WFS, have specific advantages and disadvantages which will be discussed. Yet, both methods are under continuous development, and a decision in favor of one of them should be taken from a strictly application-oriented point of view by considering relevant application-specific advantages and disadvantages in detail.