22 research outputs found
Active control of sound inside a sphere via control of the acoustic pressure at the boundary surface
Here we investigate the practical feasibility of performing soundfield
reproduction throughout a three-dimensional area by controlling the acoustic
pressure measured at the boundary surface of the volume in question. The main
aim is to obtain quantitative data showing what performances a practical
implementation of this strategy is likely to yield. In particular, the
influence of two main limitations is studied, namely the spatial aliasing and
the resonance problems occurring at the eigenfrequencies associated with the
internal Dirichlet problem. The strategy studied is first approached by
performing numerical simulations, and then in experiments involving active
noise cancellation inside a sphere in an anechoic environment. The results show
that noise can be efficiently cancelled everywhere inside the sphere in a wide
frequency range, in the case of both pure tones and broadband noise, including
cases where the wavelength is similar to the diameter of the sphere. Excellent
agreement was observed between the results of the simulations and the
measurements. This method can be expected to yield similar performances when it
is used to reproduce soundfields.Comment: 28 pages de text
Large Deformation Diffeomorphic Metric Mapping And Fast-Multipole Boundary Element Method Provide New Insights For Binaural Acoustics
This paper describes how Large Deformation Diffeomorphic Metric Mapping
(LDDMM) can be coupled with a Fast Multipole (FM) Boundary Element Method (BEM)
to investigate the relationship between morphological changes in the head,
torso, and outer ears and their acoustic filtering (described by Head Related
Transfer Functions, HRTFs). The LDDMM technique provides the ability to study
and implement morphological changes in ear, head and torso shapes. The FM-BEM
technique provides numerical simulations of the acoustic properties of an
individual's head, torso, and outer ears. This paper describes the first
application of LDDMM to the study of the relationship between a listener's
morphology and a listener's HRTFs. To demonstrate some of the new capabilities
provided by the coupling of these powerful tools, we examine the classical
question of what it means to ``listen through another individual's outer
ears.'' This work utilizes the data provided by the Sydney York Morphological
and Acoustic Recordings of Ears (SYMARE) database.Comment: Submitted as a conference paper to IEEE ICASSP 201
Kernal principal component analysis of the ear morphology
This paper describes features in the ear shape that change across a population of ears and explores the corresponding changes in ear acoustics. The statistical analysis conducted over the space of ear shapes uses a kernel principal component analysis (KPCA). Further, it utilizes the framework of large deformation diffeomorphic metric mapping and the vector space that is constructed over the space of initial momentums, which describes the diffeomorphic transformations from the reference template ear shape. The population of ear shapes examined by the KPCA are 124 left and right ear shapes from the SYMARE database that were rigidly aligned to the template (population average) ear. In the work presented here we show the morphological variations captured by the first two kernel principal components, and also show the acoustic transfer functions of the ears which are computed using fast multipole boundary element method simulations
D6.2: Intermediate Standardisation and Dissemination Activity Report
This report documents the standardisation and dissemination activities performed by the ORPHEUS project consortium from December 2015 to February 2017
Application des techniques de contrôle actif à la reproduction étendue de champs sonores basses fréquences
Using "classical" spatialization methods is not appropriate to reproduce low-frequency sound fields, due to the specificities of sound reproduction at these frequencies. Instead, some strategies inherited from active noise control could be used, which consist in using a loudspeaker array to control the sound field measured by microphones located at the surface of the volume where the sound reproduction is intended. This work aims at studying both numerically and experimentally these surfacic sound reproduction methods. First, the behaviour of set-ups using strategies of this kind has been simulated in free-field conditions. The results have then been compared to those of an active noise control experiment done in a anechoic chamber. Finally, the feasibility of performing sound reproduction using surfacic strategies in a specially-designed cabin has been studied. Results show that the cabin may accurately reproduce low-frequency plane waves traveling around a listener.La spatialisation des champs sonores basses fréquences doit satisfaire des contraintes spécifiques qui interdisent l'utilisation des techniques de restitution sonore classiques. En revanche, certaines stratégies héritées du contrôle actif du bruit offrent une solution intéressante : il s'agit d'utiliser un réseau de haut-parleurs pour contrôler le champ sonore au niveau de microphones situés en surface de la zone dans laquelle on cherche à reproduire les sons. L'objectif de cette thèse est l'étude numérique et expérimentale de ces méthodes surfaciques de reproduction sonore. Dans un premier temps, on a simulé le comportement de dispositifs utilisant ce type de stratégie en conditions de champ libre. Ces simulations ont ensuite été confrontées aux résultats d'une expérience de contrôle actif réalisée en chambre anéchoïque. Finalement, on a réalisé une étude de faisabilité concernant l'utilisation des stratégies surfaciques de reproduction sonore dans un local dédié. Les résultats montrent que ce local pourrait permettre de reproduire avec précision des ondes planes basses fréquences se propageant autour d'un auditeur
3D reproduction of low-frequency sound fields using the boundary pressure control method
International audienc