In-house alert sounds detection and direction of arrival estimation to assist people with hearing difficulties

A prototype of a low-cost, wearable system is presented to assist persons with hearing impairments by detecting in-house alert sounds and estimating their direction of arrival (DOA). The prototype is composed of a circular microphone array, a small microcomputer, and motors for vibration alerting. The array includes five microphones uniformly distributed on the outer surface of a ring with circumference comparable to human waist. Each microphone is connected to one of the analog inputs of the microcomputer. The power of the microphone signals is analyzed to detect alert sounds. Upon the detection of an alert sound, a low-complexity time-difference of arrival method is used to determine the sound DOA with mean error of 14.1°. The user is notified about the detection of alert sound and its DOA by vibrating the closest motor to the sounds source. The time required to detect and localize an alert sound is around 35 msec.