We present Input Finger Detection (IFD), a novel technique for  nonvisual touch screen input, and its application, the Perkinput  text entry method. With IFD, signals are input into a device with  multi-point touches, where each finger represents one bit, either  touching the screen or not. Maximum likelihood and tracking  algorithms are used to detect which fingerstouch the screen based  on user-set reference points. The Perkinput text entry method uses  the 6-bit Braille encoding with audio feedback, enabling one- and  two-handed input.