1. A method of operating a motion-capture system, the method including: monitoring at least three vibration sensors coupled to a motion-capture system; and in response to detection of vibrations generated by contact of an object with a surface of a first medium, tracking a position of the object by: detecting a first vibration through the first medium by a first vibration sensor; detecting a second vibration through a second medium by at least a second and a third vibration sensor, wherein the first medium is different from the second medium; measuring a time difference of arrival (TDOA) of the second vibration at the second and third vibration sensors with respect to the TDOA of the first vibration at the first vibration sensor and mapping surface locations that satisfy the TDOA, whereby the TDOA of the second vibration at the second and third vibration sensors differs with respect to the TDOA of the first vibration at the first vibration sensor because the second vibration travels through the second medium at a different velocity that the first vibration travels through the first medium; calculating a distance from the object to the second and third vibration sensors based on the respective TDOAs; and determining location information for the object relative to the vibration sensors based on the mapped TDOA surface locations.