In many research fields of engineering and acoustics, the image-source model represents one of the most popular tools for the simulation of sound fields in virtual reverberant environments. This can be seen as a result from the relative simplicity and flexibility of this particular method. However, the associated computational costs constitute a well known drawback of image-source implementations, as the required simulation times grow exponentially with the considered reflection order. This paper proposes a method that allows for a fast synthesis of room impulse responses according to the image-source technique. This is achieved by modeling the diffuse reverberation tail as decaying random noise, where the decay envelope for the considered acoustic environment is determined according to a recently proposed method for the prediction of energy decay curves in image-source simulations. The diffuse reverberation model presented in this paper thus produces impulse responses that are representative of the specific virtual environment under consideration (within the general assumptions of geometrical room acoustics), in contrast to other artificial reverberation techniques developed on the basis of perceptual measures or assuming a purely exponential energy decay. Furthermore, since image-source simulations are only used for the computation of the early reflections, the proposed approach achieves a reduction of the computational requirements by up to two orders of magnitude for the simulation of full-length room impulse responses, compared to a standard image-source implementation.

This paper describes a new method for the online parameter optimization of various models used to represent the target dynamics in particle filters. The optimization is performed with an evolutionary strategy algorithm, by using the performance of the particle filter as a basis for the objective function. Two different approaches to forming the objective function are presented: the first assumes knowledge of the true source position during the optimization, and the second uses the position estimates from the particle filter to form an estimate of the current ground-truth data. The new algorithm has low computational complexity and is suitable for real-time implementation. A simple and intuitive real-world application of acoustic source localization and tracking is used to highlight the performance of the algorithm. Results show that the algorithm converges to an optimum tracker for any type of dynamics model that is capable of representing the target dynamics.

Wideband robust direction of arrival estimation using microphone arrays is associated with computationally complex algorithms, unsuitable for implementation on low power devices. This paper improves on the computational complexity by devising an algorithm based on steered response interpolation combined with steered response power estimation employing root solving. The new algorithm is implemented in a PC-based realtime system and has been compared to Root-MUSIC and Far-Field SRP-PHAT. The comparison was performed with regards to computational load and robustness to noise and reverberation in a real room environment. The results show that the new algorithm is the most computationally efficient, while providing superior robustness compared to Root-MUSIC.