Chest sound pick-up using a multisensor array

This paper proposes a method of evaluating and improving the ability of a multisensor array to pick up specific sounds from the chest. The focus index (FI) is a performance metric created to evaluate the focus achieved by a near-field beamformer and it can be applied to optimize sensor arrays for a number of applications. The FI can guide the user, for instance, in selecting an appropriate number of sensors, or determining if a subbanding or other beamforming algorithm is necessary. A related performance metric, the adjusted focus index (AFI), is proposed. The AFI describes the degree of focus relative to the point where the power is maximal regardless of whether it corresponds to the intended focus location. The validity and usefulness of the FI and AFI are shown through empirical trials and simulations as well as through experimental measurements. The FI and AFI have been shown to be useful in the optimization of many multisensor arrangements, including linear, circular, rectangular, and three-dimensional arrays