To specify that a sound is a gunshot requires special aural examinations, high resolution waveform analysis, and the presence or absence of precursor N-waves. Determining the exact location of the source of an impulsive type sound calls for a high quality tape recording made on site, knowledge of the approximate location of the microphone, and a scaled map of the area. In 1978, at the request of the House Select Committee on Assassinations (HSCA), Bolt, Beranek and Newman, Inc., studied recordings of police radio and traffic during the assassination, and Mark R. Weiss and Ernest Aschkenasy, Queens College, City University of New York, conducted an independent analysis of the alleged third gunshot recorded on the Dallas Police Department radio system. Based primarily on the acoustical analyses performed by BBN and Weiss and Aschkenasy indicating that there were gunshots in Dealey Plaza from both the Texas School Book Depository building (where Lee Harvey Oswald allegedly fired three gunshots) and the grassy knoll area (one gunshot) during Kennedy's assassination, the HSCA found, in part, that 'scientific acoustical evidence establishes a high probability that two gunmen fired at President John F Kennedy.' A concluding section, to appear in next month, reports on a review and the findings of the FBI and the analyses conducted by the National Research Council.