Blind Directional Room Impulse Response Parameterization from Relative Transfer Functions

Acquiring information about an acoustic environment without conducting dedicated measurements is an important problem of forthcoming augmented reality applications, in which real and virtual sound sources are combined. We propose a straightforward method for estimating directional room impulse responses from running signals. We adaptively identify relative transfer functions between the output of a beam-former pointing into the direction of a single active sound source and the complete set of spherical harmonics domain signals, representing all directions. To this end, estimation is performed with a frequency domain recursive least squares algorithm. Then, parameters such as the directions of arrival of early reflections and the reverberation time are extracted. Estimation of the direct-to-reverberant ratio requires dedicated processing. We show examples of successful estimation from speech signals, based on a simulated and a measured response.