Albenzio Cirillo

Source Localization in Reverberant Environments by Consistent Peak Selection

Acoustic source localization in the presence of reverberation is a difficult task. Conventional approaches, based on time delay estimation performed by generalized cross correlation (GCC) on a set of microphone pairs, followed by geometric triangulation, are often unsatisfactory. Prefiltering is usually adopted to reduce the spurious peaks due to reflections. In this work an alternative strategy is proposed, based on the concept that secondary peaks of the GCCs can be crucial in order to correctly locate the source. More specifically, an iterative weighting procedure is introduced, based on the rationale that peaks corresponding to the actual source position should be consistently weighted. The position estimate is then refined by use of an effective and fast clustering technique. Experimental results on simulated data demonstrate the effectiveness of the proposed solution.

Sound mapping in reverberant rooms by a robust direct method

Direct methods estimate the position of an acoustic source by sampling the environment through a set of properly placed microphones. SRP-Phat is probably the most popular direct method. It is based on computation of the generalized cross- correlation (GCC) of signals on a grid of preselected points. Anyway, in the presence of reverberation, the functional employed by SRP-Phat can be very irregular from point to point, thus making the source localization a difficult task. In this paper, a new functional is presented that regularizes the SRP- Phat approach and makes it more efficient the use of optimization algorithms to further refine the source position estimation. After a brief introduction, the proposed approach is described and compared to SRP-Phat on simulated and real data at different reverberation levels.

Improved TDOA disambiguation techniques for sound source localization in reverberant environments

Given a single sound source in a non reverberant environment, an estimate of the Time Difference Of Arrival (TDOA) between microphones can be obtained by observing the time value at which the cross correlation of the two microphone signals displays a maximum. In the presence of reverberation, however, the cross correlation function displays a great number of local maxima caused by reflected signals blending unpredictably. This results in TDOA estimation ambiguity, making correct source localization impossile. The aim of this work is to present an improved disambiguation algorithm and compare it to existing algorithms in terms of estimation accuracy and processing time.

A new consistency measure for localization of sound sources in the presence of reverberation

Sound source localization is an important task in many practical applications. Among existing methods, the Linear Intersection algorithm is a popular technique and performs well in noisy conditions without requiring high computational costs. Unfortunately the performance of Linear Intersection is seriously hampered by the presence of reverberation, which is quite common in closed environments. In order to overcome this limitation, the Optimal Line Selection technique was proposed in the past. In this paper some important modifications of this technique are presented and described. Results on simulated and real data confirm the quality of the proposed solution.

Prefiltering Techniques on Consistent Peak Selection for Talker Position Estimation in Reverberant Rooms

Hands-free communication systems need to isolate a single talker contribution in a distant talking situation and in the presence of environmental noises or other acoustic events. Sound source localization is an essential part of this process. However, localization methods that are actually based on time delay estimation (TDE) yield worse performances as reverberation time increases. As the majority of the technologies adopting hands-free systems are applied into bounded environment, a strategy to limit the effect of reverberation is due. The Optimal Line Selection algorithm demonstrated to perform well in case of localization in different reverberant conditions. In this paper the behavior of this estimator will be examined in case of cepstral prefiltering.