Robust sound localization in 0.18 μm CMOS

This paper presents a hardware implementation of a sound localization algorithm that localizes a single sound source by using the information gathered by two separated microphones. This is achieved through estimating the time delay of arrival (TDOA) of sound at the two microphones. We have used a TDOA algorithm known as the "phase transform" to minimize the effects of reverberations and noise from the environment. Simplifications to the chosen TDOA algorithm were made in order to replace complex operations, such as the cosine function, with less expensive ones, such as iterative additions. The custom digital signal processor implementing this algorithm was designed in a 0.18-μm CMOS process and tested successfully. The test chip is capable of localizing the direction of a sound source within 2.2° of accuracy, utilizing approximately 30 mW of power and 6.25 mm² of silicon area.