Detecting daily activity of solitary living elderly persons.

We report on an activity monitoring system for elderly persons living alone. Caregivers would like to know whether the person is talking during their daily activity. Our monitoring system consists of a recorder and a personal computer. The recorder, attached to the subject's chest, employs two microphones, a tri-axis accelerometer, two low-power amplifiers, a low-power microcomputer (MC) and a 2GB micro SD Memory Card (SDMC). One of the microphones is set in the direction of the chest for recording the person's voice, and the other microphone is set to the opposite side for recording surrounding sound. The microphone outputs and the accelerometer outputs are sent to the MC’s 10 bit analog to digital converters and sampled at 4000Hz and 50Hz, respectively. The MC detects the length of the conversation time from the microphone outputs, and the posture and behavior are detected from the accelerometer outputs every 5 seconds. The detected time, posture and behavior are stored in the SDMC. The data can be downloaded from the memory card and sent to appropriate stations. The system is used to monitor the health and physical conditions during daily life of elderly persons living alone.