Extraction of exterior field from a mixed sound field for 2D height-invariant sound propagation

Any sound field caused by one or more sound sources takes the form of an interior, exterior or a mixed sound field based on the source locations. The recording and reproduction of interior or exterior sound fields in terms of harmonic decomposition has been extensively studied in the literature, however the challenging task of separating them in a mixed field remains largely unexplored. But in nature, the interior and exterior sound fields often co-exist, hence their isolation can be very useful in many acoustic processes. In this paper, we discuss a method to extract the exterior field from a mixed sound field for 2D height-invariant sound propagation. Such an extraction method can be employed to record a sound field in a noisy or interfered room or to perform dereverberation in a reverberant room where the sound fields due to the source signal and its reflections superimpose each other. We demonstrate two practical uses of the proposed method in the forms of (i) an exterior sound field recording in a mixed wave field and (ii) speech dereverberation in a simulated reverberant room.