SPEECH RECORDINGS REPRESENT AN IMPORTANT TOOL IN CRIMINAL INVESTIGATIONS. TOO OFTEN, HOWEVER, THE QUALITY OF THESE RECORDINGS IS INADEQUATE TO SATISFY THE NEEDS OF FORENSIC EXAMINERS. AUDIO DEGRADATIONS DUE TO BACKGROUND NOISE, SEVERE REVERBERATION, HUM, AND EQUIPMENT MALFUNCTION ARE FREQUENTLY DIFFICULT OR IMPOSSIBLE TO REMOVE USING CONVENTIONAL AUDIO FILTERING TECHNIQUES. THE IDIFIL SYSTEM HAS CAPABILITIES SUBSTANTIALLY GREATER THAN THOSE OFFERED BY CONVENTIONAL ELECTRONIC FILTERS AND AUTOMATIC GAIN AMPLIFIERS USED BY FORENSIC TECHNIQUES TO IMPROVE THE QUALITY OF DEGRADED VOICE RECORDINGS. THIS COMPUTER-BASED SPEECH ENCHANCEMENT SYSTEM PROVIDES A LARGE VARIETY OF DIGITAL PROCESSING TOOLS, INCLUDING FINE-GRAIN SPECTRAL ANALYSIS, VOICE LEVEL EQUALIZATION, INTERACTIVE SPEECH DIGITAL FILTERING, PREDICTIVE DECONVOLUTION, AND ADAPTIVE FILTERING. THE ADAP IS A REAL-TIME SPECIAL-PURPOSE AUDIO COMPUTER THAT MAKES EXTENSIVE USE OF SIGNAL PROCESSING AND DIGITAL CIRCUIT TECHNOLOGY. IT IS COMPRISED OF OVER 135 INTEGRATED CIRCUITS, ALONG WITH ANALOG-TO-DIGITAL AND DIGITAL-TO-ANALOG CONVERTERS, ANALOG DISCRETE MODULES, SAMPLING FILTERS, AND POWER SUPPLIES. THE OPERATION OF THE IDIFIL SYSTEM AND THE ADAP IS DESCRIBED AND ILLUSTRATED. REFERENCES ARE CITED. (DEP)