NEW DEVELOPMENTS IN LOW-BIT RATE VIDEOTELEPHONY FOR PEOPLE WHO ARE DEAF

This study was designed to evaluate the picture quality requirements F or three visual communication modes: speechreading, fingerspelling, an d sign language. Video recordings of everyday spoken, fingerspelled, a nd signed sentences were made, and some recordings were processed usin g a computer simulation of the IBIDEM technology: a videophone based o n a novel type of visual sensor. This retina-like sensor, implemented in the camera, has a high resolution in the central part and a degradi ng resolution in the peripheral part of the picture. Two independent v ariables were examined: frame rate (10 and 15 Frames per second) and s patial resolution (6000 and 8000 pixels per frame). Twenty-four people who were prelingually deaf participated, 8 in each communication mode . The results showed a marked effect of frame rate on speechreading. F ingerspelling and sign language were not affected by frame rate, and s patial resolution had no effect on any of the three communication mode s.