A force sensing device for computer or electronic devices. The force is estimated by comparing the reflected ultrasonic energy on the touch interface. The force sensing device is configured to determine an amount of force applied, and changes in amounts of force applied, by the user when contacting a device, such as a touch device, and which can be incorporated into devices using touch recognition, touch elements of a graphical user interface, and touch input or manipulation in an application program. Additionally, the force sensing device may determine an amount of force applied, and changes in amounts of force applied, by the user when contacting a device, such as a touch device, and in response thereto, provide additional functions available to a user of a touch device, track pad, or the like.