In 1978 the acoustics firm Bolt, Beranek and Newman (BBN) analyzed a tape recording made of the Dallas Police Department (DPD) channel one. On August 20, 1978 BBN performed a test in Dealey Plaza by shooting several shots from two locations at targets placed on Elm Street in approximately the positions the limousine was at the time of three likely shots. The test shots were recorded by microphones placed on Houston Street and Elm Street which matched the route of the motorcade. In September 1978 BBN testified to the HSCA that it had compared the test shots to the DPD tape and found four shots on the DPD tape. But one of the four matches was the most controversial, a shot from the grassy knoll, and BBN only gave it a 50-50 chance of really being a shot from the grassy knoll. So HSCA hired two acoustical experts, Weiss and Aschkenasy (W&A) to resolve the uncertainty of the grassy knoll shot. W&A identified the echo paths of the grassy knoll shot and stated with a confidence of 95% or better that one of the four shots was fired from the grassy knoll. The HSCA ended at the beginning of 1979 and no further work was done on the acoustical evidence by the HSCA. However, the HSCA suggested that more work should be done, but the DOJ refused to do so. Instead, it assigned the National Academy of Sciences (NAS) the task of refuting the HSCA acoustical analysis. In May 1982 the NAS panel issued a report claiming that there were no shots on the DPD tape. In August 1983 I wrote a  Rebuttal to Ramsey which points out many errors in the NAS report, and reaffirms the accuracy of the HSCA studies.

     In the late 1980's I wrote some BASIC programs on the Commodore which simulate the HSCA acoustical analysis. One of the first programs was a test of method which analyzes three BBN test shots in order to identify possible echo producing objects and test the calculation process. I have converted it to QBASIC for the IBM and included it in the file named  BBNstudy.bas .
The other program simulates the W&A study by searching for matching echo patterns for each DPD tape impulse. It is converted to QBASIC and included in the file named  DPDstudy.bas .