Despoina Pavlidi

Real-Time Multiple Sound Source Localization and Counting Using a Circular Microphone Array

In this work, a multiple sound source localization and counting method is presented, that imposes relaxed sparsity constraints on the source signals. A uniform circular microphone array is used to overcome the ambiguities of linear arrays, however the underlying concepts (sparse component analysis and matching pursuit-based operation on the histogram of estimates) are applicable to any microphone array topology. Our method is based on detecting time-frequency (TF) zones where one source is dominant over the others. Using appropriately selected TF components in these “single-source” zones, the proposed method jointly estimates the number of active sources and their corresponding directions of arrival (DOAs) by applying a matching pursuit-based approach to the histogram of DOA estimates. The method is shown to have excellent performance for DOA estimation and source counting, and to be highly suitable for real-time applications due to its low complexity. Through simulations (in various signal-to-noise ratio conditions and reverberant environments) and real environment experiments, we indicate that our method outperforms other state-of-the-art DOA and source counting methods in terms of accuracy, while being significantly more efficient in terms of computational complexity.

Localizing multiple audio sources in a wireless acoustic sensor network

In this work, we propose a grid-based method to estimate the location of multiple sources in a wireless acoustic sensor network, where each sensor node contains a microphone array and only transmits direction-of-arrival (DOA) estimates in each time interval, reducing the transmissions to the central processing node. We present new work on modeling the DOA estimation error in such a scenario. Through extensive, realistic simulations, we show that our method outperforms other state-of-the-art methods, in both accuracy and complexity. We also present localization results of real recordings in an outdoor cell of a sensor network. HighlightsWe examine localization in a WASN where each node transmits DOA estimates.We perform DOA estimation error modeling and examine the merging of nearby sources.We present a real-time low-complexity method for localization of multiple sources.Results indicate the advantages of our method in accuracy/computational complexity.We present localization results of real recordings in an outdoor cell of a sensor network.

Real-time multiple sound source localization using a circular microphone array based on single-source confidence measures

We propose a novel real-time adaptative localization approach for multiple sources using a circular array, in order to suppress the localization ambiguities faced with linear arrays, and assuming a weak sound source sparsity which is derived from blind source separation methods. Our proposed method performs very well both in simulations and in real conditions at 50% real-time.

3D localization of multiple sound sources with intensity vector estimates in single source zones

This work proposes a novel method for 3D direction of arrival (DOA) estimation based on the sound intensity vector estimation, via the encoding of the signals of a spherical microphone array from the space domain to the spherical harmonic domain. The sound intensity vector is estimated on detected single source zones (SSZs), where one source is dominant. A smoothed 2D histogram of these estimates reveals the DOA of the present sources and through an iterative process, accurate 3D DOA information can be obtained. The performance of the proposed method is demonstrated through simulations in various signal-to-noise ratio and reverberation conditions.

Source counting in real-time sound source localization using a circular microphone array

Recently, we proposed an approach inspired by Sparse Component Analysis for real-time localization of multiple sound sources using a circular microphone array. The method was based on identifying time-frequency zones where only one source is active, reducing the problem to single-source localization for these zones. A histogram of estimated Directions of Arrival (DOAs) was formed and then processed to obtain improved DOA estimates, assuming that the number of sources was known. In this paper, we extend our previous work by proposing three different methods for counting the number of sources by looking for prominent peaks in the derived histogram based on: (a) performing a peak search, (b) processing an LPC-smoothed version of the histogram, (c) employing a matching pursuit-based approach. The third approach is shown to perform very accurately in simulated reverberant conditions and additive noise, and its computational requirements are very small.

3D DOA estimation of multiple sound sources based on spatially constrained beamforming driven by intensity vectors

Sound source localization in three dimensions with microphone arrays is an active field of research, applicable in sound enhancement, source separation, and sound field analysis. In this contribution we propose a method for three dimensional multiple sound source localization in reverberant environments. We employ a spatially constrained steered response beamformer on a spherical sector centered at the direction of arrival (DOA) estimates of the intensity vector. Experiments are performed in both simulated and real acoustical environments with a spherical microphone array for multiple sound sources under different reverberation and signal-to-noise ratio (SNR) conditions. The performance of the proposed method is compared with our previously proposed work and a subspace method in the spherical harmonic domain. The results demonstrate a significant improvement in terms of localization accuracy.

The MusiNet project: Towards unraveling the full potential of Networked Music Performance systems

The MusiNet research project aims to provide a comprehensive architecture and a prototype implementation of a complete Networked Music Performance (NMP) system. In this paper we describe the current status of the project, focusing on critical decisions regarding the systems architecture and specifications, the low delay audio and video coding techniques to be employed, the media relay design, and the synchronous and asynchronous collaboration algorithms to be adopted.

3D localization of multiple audio sources utilizing 2D DOA histograms

Steered response power (SRP) techniques have been well appreciated for their robustness and accuracy in estimating the direction of arrival (DOA) when a single source is active. However, by increasing the number of sources, the complexity of the resulting power map increases, making it challenging to localize the separate sources. In this work, we propose an efficient 2D histogram processing approach which is applied on the local DOA estimates, provided by SRP, and reveals the DOA of multiple audio sources in an iterative fashion. Driven by the results, we also apply the same methodology to local DOA estimates of a known subspace method and improve its accuracy. The performance of the presented algorithms is validated with numerical simulations and real measurements with a rigid spherical microphone array in different acoustical conditions: for multiple audio sources with different angular separations, various reverberation and signal-to-noise ratio (SNR) values.

Development and evaluation of a digital MEMS microphone array for spatial audio

We present the design of a digital microphone array comprised of MEMS microphones and evaluate its potential for spatial audio capturing and direction-of-arrival (DOA) estimation which is an essential part of encoding the soundscape. The device is a cheaper and more compact alternative to analog microphone arrays which require external - and usually expensive - analog-to-digital converters and sound cards. However, the performance of such digital arrays for DOA estimation and spatial audio acquisition has not been investigated. In this work, the efficiency of the digital array for spatial audio is evaluated and compared to a typical analog microphone array of the same geometry. Our results indicate that our digital array achieves the same performance as its analog counterpart, thus offering a cheaper and easily deployable device, suitable for spatial audio applications.

The MusiNet project: Addressing the challenges in Networked Music Performance systems

This paper presents the progress in the MusiNet research project, which aims to provide a comprehensive architecture and a prototype implementation of a Networked Music Performance (NMP) system. We describe the Musinet client and server components, and the different approaches followed in our research effort in order to culminate in the most appropriate scheme in terms of delay and quality for the audio and video streams involved. We also describe the MusiNet user interface, which allows an integrated communication between the participants and the proposed NMP system.