Multiple source separation in the frequency domain using negative beamforming
Pedro Gómez‐Vilda, A. Álvarez-Marquina, V. Nieto-Lluís, V. Rodellar-Biarge, R. Martínez-Olalla · 2001
Abstract The localization of acoustic sources in a room is essential in many applications, as security monitoring, video conferencing, automatic scene analysis [6], reverberation canceling [5], or robust Speech Recognition under multiple-party effect [7]. Through the present paper the design and operation of a negative beamformer for multiple source speech separation will be presented. The problems found for its proper operation when multiple sources are present on the same band will be pointed out and the solutions found will be commented and discussed showing the results of real experiments carried out on a recording scenario. 1. Introduction The joint application of acoustic source localization (ASL) and scene video tracking is becoming an important support technology for hybrid audio-video platforms, as for example in video-conferencing or security systems in public places. For acoustic source localization positive array beamforming have been traditionally used with great success [4]. Nevertheless, positive array beamformers present certain inconveniences. These structures show non-neglectable side lobes which demand an important computational power to be reduced. The aperture of the main lobe is usually wide, and to narrow it either more sensors are needed or more power-demanding algorithms have to be used. On the other hand large number of sensors make signal acquisition and conditioning interfaces expensive, rendering the system expensive and difficult to install and operate. Negative beamformers, on the other side do not require a large number of sensors, and their extension to beam-like detection is straight forward. Nevertheless negative beamformers need to be adapted to broad-band signal enhancement and tracking. In a preliminary paper [2] the authors have shown how to track and separate individual sinusoidal sources in different bands, and to extend the results to broad-band (speech) signals. Through this paper the separation of sources on the same band is addressed. Section 2 reviews the basics of negative beamforming to deal with broad-band signals. In Section 3 the problem of multiple source separation is treated. Section 4 shows some practical study cases.