smartphones today are becoming both ubiquitous, as well as powerful with significant processing, networking and storage capabilities. In parallel, a critical development in modern smartphones come from the ability to embed multiple sensors in them for fine grained sensing of several phenomena. For instance, a modern smartphone like Samsung Galaxy S4 has built-in sensors that can measure acceleration, ambient temperature, pressure, humidity, light intensity, magnetic intensity sound intensity, and much more, with high sampling rates. The LIS344ALH accelerometer sensor in the Samsung Galaxy S4 phone [ij can sample up to 200 samples per second, and the sampling rate is programmable. Furthermore, numerous studies are been conducted to optimize the performance of smartphone sensors today from the perspective of accuracy energy efficiency and processing speed [2]
There is a clear and tangible reason for the continued innovation in sensing capabilities of smartphones today, and that lies in numerous innovative and societally useful applications leveraging smartphone sensors. The most significant one is emerging in the domain of health-care and well-being. In [7] smartphone accelerometer is leveraged to detect the gait of a subject with applications for fall detection in elder care. The acoustic sensors in smartphones have been leveraged for self-localization of smartphones in [5]. More recently