NCJ Number
57740
Date Published
1977
Length
5 pages
Annotation
THE NEED FOR SATISFACTORY TECHNIQUES FOR AUTHENTICATING TAPE RECORDINGS IS UNDERSCORED IN THIS PAPER FOCUSING ON EXISTNG METHODS FOR DETECTING SPLICES ON, OMISSIONS FROM, AND ADDITIONS TO TAPE RECORDINGS.
Abstract
THE PROBLEM OF TAPE RECORDING AUTHENTICATION IS A PARTICULARLY SERIOUS ONE IN SITUATIONS, ESPECIALLY COURT CASES, WHERE ONE OF THE PARTIES CLAIMS THAT THE TAPES HAVE BEEN DOCTORED. MOREOVER, NO MATTER WHAT INDIVIDUAL OR AGENCY HAS MADE THE TAPE RECORDING, IF IT IS TO BE AUTHENTICATED, THE RECORDING MUST BE TREATED AS THOUGH IT HAS BEEN TAMPERED WITH OR FRAUDULENTLY CONSTRUCTED. THUS, THE EXAMINATION MUST BE BOTH VIGOROUS AND THOROUGH. AN APPROACH TO THIS PROBLEM HAS BEEN DEVELOPED AT THE INSTITUTE FOR ADVANCED STUDY OF THE COMMUNICATION PROCESSES, UNIVERSITY OF FLORIDA. IT INCLUDES THE FOLLOWING: (1) VISUAL INSPECTION OF THE RECORDING TAPE FOR EVIDENCE OF SPLICES, (2) MICROSCOPIC AND RELATED EXAMINATION OF THE OXIDE SURFACE OF THE TAPE FOR PHYSICAL EVIDENCE OF START-STOP ACTIVITY AND RERECORDING, (3) AUDITORY EXAMINATION FOR PERCEPTUAL EVIDENCE OF TAMPERING (CLICKS, CHANGES IN SOUND LEVEL, ETC.), (4) VISUAL ANALYSIS OF THE SIGNAL BY MEANS OF A OSCILLOSCOPE, (5) VISUAL ANALYSIS OF THE SIGNAL FROM PERMANENT RECORDS OF THE NOISE FIELDS ON THE TAPE RECORDING, (7) AMPLIFICATION OF THE TAPE SECTIONS WHERE NO SIGNAL APPEARS PRESENT IN ORDER TO DETECT ERASURES AND STOP-START ACTIVITY, AND (8) SPECTROGRAPHIC AND RELATED ANALYSIS OF THOSE PORTIONS OF THE TAPE WHERE THERE APPEARS TO BE SOME EVIDENCE OF TAMPERING. (AUTHOR ABSTRACT MODIFIED--KBL)