Measurement of water level in a monitoring system of a bathroom

Developing a monitoring system of bathroom is important for preventing accidents in bathrooms. Although CCD camera is easily imagined as a monitoring device, it is unsuitable by various problems such as violation of one´s privacy, expensiveness, moistures on the lens, and so on. This paper proposes a new monitoring system by immersing a pipe with an acoustic sensor inside into the bathtub. By the system, we can obtain not only direct sound information from the people in the bathroom, but also the information on the water level of the bathtub. For the measurement of the water level, stationary waves inside the pipe are used and the adaptive selections of data window and optimal modes are considered. Experiments demonstrate that the accurate water level measurement is achieved with the proposed method regardless of sound environment.