A Theoretical study on the placement of microphone arrays for improving the localization accuracy of a fall

Falling is a common health problem for elderly. To address the problem, we are currently developing an acoustic fall detection system, FADE, which automatically detects a fall and reports to the caregiver. Of great importance of the fall detection system is a low false alarm rate that can be achieved by knowing where the acoustic signal comes from. The previous work showed the sound source localization can be determined by using an 8-microphone circular array, but the accuracy varies when placing the array at different positions. To further improve the localization accuracy, a second array can be added. In this paper we investigate the variations of localization accuracy of a fall signal when one or two arrays are placed at different positions in a room. The accuracy is evaluated by the Cramér-Rao Lower Bound (CRLB). The CRLB aids the determination of the best theoretical placement of one or two arrays in a room for locating the sound source.