The work presented in this paper comes as a part of a project which aims at developing an auditory system for a mobile robot. It presents a sound source localization strategy which enables the sensing of signals within a direction of arrival and frequency domain of interest while rejecting other data. A rapid prototyping method is proposed to design filter-sum beamformers on the basis of convex optimization. This method is well-suited to robotics applications as it copes with real-time constraints and allows the localization of broadband signals such as human voice. Numerous simulation results are used to illustrate the reasoning.