Extraction of 3D Information from Circular Array Measurements for Auralization with Wave Field Synthesis

Abstract

The state of the art of wave field synthesis (WFS) systems is that they can reproduce sound sources and secondary (mirror image) sources with natural spaciousness in a horizontal plane, and thus perform satisfactory 2D auralization of an enclosed space, based on multitrace impulse response data measured or simulated along a 2D microphone array. However, waves propagating with a nonzero elevation angle are also reproduced in the horizontal plane, which is neither physically nor perceptually correct. In most listening environments to be auralized, the floor is highly absorptive since it is covered with upholstered seats, occupied during performances by a well-dressed audience. A first-order ceiling reflection, reaching the floor directly or via a wall, will be severely damped and will not play a significant role in the room response anymore. This means that a spatially correct WFS reproduction of first-order ceiling reflections, by means of a loudspeaker array at the ceiling of the auralization reproduction room, is necessary and probably sufficient to create the desired 3D spatial perception. To determine the driving signals for the loudspeakers in the ceiling array, it is necessary to identify the relevant ceiling reflection(s) in the multichannel impulse response data and separate those events from the data set. Two methods are examined to identify, separate, and reproduce the relevant reflections: application of the Radon transform, and decomposition of the data into cylindrical harmonics. Application to synthesized and measured data shows that both methods in principle are able to identify, separate, and reproduce the relevant events.

Acoustic Reflector Localization: Novel Image Source Reversion and Direct Localization Methods

“…0.90 m. The simulated microphone array was composed by 48 evenly spaced microphones placed in two concentric circles, with the inner circle of radius 0.083 m, and outer circle of 0.104 m radius, similar to the prototype designed for our experimental apparatus. Its circular configuration was chosen since it has been proved to be effective for analyzing acoustic 3D information [55]. The center of the microphone array on the horizontal plane was randomly chosen.…”

Análisis De La Acústica De Salas Mediante La Utilización De Arrays De Micrófonos Circulares

“…Como ya se ha comentado, los arrays circulares de micrófonos son conocidos por sus idoneidad en un completo rango azimutal y por poseer una geometría adecuada para el procesado modal de arrays, lo cual permite mejoras significativas en el análisis del campo de onda, [10,14,26,27]. La geometría de array utilizada a partir de ahora es la mostrada en la Figura 2.9.…”

“…Este requerimiento físico puede ser un problema en algunas aplicaciones prácticas (por ejemplo en el Array 3 de la Sección 6.3 se requeriría un cilindro mayor a 40; 3 cm). Para evitar la amplificación del ruido debido a grandes valores de ecualización, Parthy et al [42] propuso el uso de los filtros regularizados Tikhonov, los cuales vienen dados por 27) donde w k (kR) = B 1 k (kR) y es el coeficiente de regularización. El uso de la regularización, además de mejorar la ganancia de ruido blanco, produce un beampattern más robusto y suavizado.…”

“…Esto era debido a que el término de velocidad V(k ; !) para un micrófono de figura en ocho combinado con el término de presión P resultaba el patrón de un micrófono cardioide, el cuál era idóneo desde una perspectiva práctica [27]. De tal forma, el array estaba compuesto por dos micrófonos cardioides de la marca Earthworks SR 30 sujetos en el final de una barra de 2 metros de longitud y anclada en un motor giratorio formando entre sí 180 como se aprecia en la Figura 5.…”

Application of a Wave Field Synthesis (WFS) Audio System based on A2B protocol: a case study

“…This paper deals with the design and the installation of a WFS system [1], which overcomes the above limitation. The system is composed by 20 soundbars, each 1 m long and equipped with 8 loudspeakers, for a total number of 160 loudspeakers.…”