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Theses

Ambisonie d'ordre élevé en trois dimensions : captation, transformations et décodage adaptatifs de champs sonores

Abstract : Sound field synthesis is an active research domain with various musical, multimedia or industrial applications. In the latter case, the accurate reconstruction of the sound field is targeted, which involves answering several scientific questions. Using arrays of microphones and loudspeakers, the capture, synthesis and accurate reconstruction of sound fields are theoretically possible. However, for practical applications, the arrangement of the loudspeakers and the acoustic influence of the restitution room are critical factors to consider in order to ensure the accurate reconstruction of the sound field.In this context, this thesis proposes methods and techniques for the capture, transformations and accurate reconstruction of sound fields in three dimensions based on the Higher Order Ambisonics (HOA) method. A spherical configuration for the array of microphones and loudspeakers is proposed. It follows a fifty-node Lebedev grid that enables the capture and reconstruction of the sound field up to order 5 with HOA formalism. The limitations of this approach, such as the spatial aliasing, are studied in detail.A transformation operation of the sound field is also proposed. The formulation is established in the spherical harmonics domain and enables a directional filtering on the sound field prior to the decoding step.For the reconstruction of the sound field, and original approach, also established in the spherical harmonics domain, can take into account the acoustic influence of the restitution room and the defects of the playback system. This treatment then adapts the synthesis of sound fields to the restitution room, maintaining the theoretical formalism established in free field.Finally, an experimental validation of methods and techniques developed in the thesis is made. In this context, a digital signal processing toolkit is developed. It process in real-time the microphones, ambisonics, and loudspeaker signals for the sound field capture, transformations, and decoding.
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https://tel.archives-ouvertes.fr/tel-01544953
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Submitted on : Thursday, June 22, 2017 - 12:26:52 PM
Last modification on : Wednesday, March 20, 2019 - 1:26:43 AM
Long-term archiving on: : Saturday, December 16, 2017 - 7:24:13 AM

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  • HAL Id : tel-01544953, version 1

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Pierre Lecomte. Ambisonie d'ordre élevé en trois dimensions : captation, transformations et décodage adaptatifs de champs sonores. Acoustique [physics.class-ph]. Conservatoire national des arts et metiers - CNAM, 2016. Français. ⟨NNT : 2016CNAM1076⟩. ⟨tel-01544953⟩

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