A concept for a research tool for experiments with cochlear implant users

APEX, an acronym for computer Application for Psycho-Electrical experiments , is a user friendly tool used to conduct psychophysical experiments and to investigate new speech coding algorithms with cochlear implant users. Most common psychophysical experiments can be easily programmed and all stimuli can be easily created without any knowledge of computer programing. The pu lsatile stimuli are composed off-line using custom-made MATLAB (Registered trademark of The Mathworks, Inc., http://www.mathworks.com) functions and a re stored on hard disk or CD ROM. These functions convert either a speech s ignal into a pulse sequence or generate any sequence of pulses based on the parameters specified by the experimenter. The APEX personal computer (PC) software reads a text file which specifies the experiment and the stimuli, controls the experiment, delivers the stimuli to the subject through a digi tal signal processor (DSP) board, collects the responses via a computer mou se or a graphics tablet, and writes the results to the same file. At presen t, the APEX system is implemented for the LAURA (Registered trademark of Ph ilips Hearing Implants) cochlear implant. However, the concept-and many par ts of the system-is portable to any other device. Also, psycho-acoustical e xperiments can be conducted by presenting the stimuli acoustically through a sound card. (C) 2000 Acoustical Society of America. [S0001-4966(00)00912- 7].