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1.1 U.S. ~t or Jultlcl 111111.8 NlilonallMtftut. or .Julltlee 7111,. oo."'Umt>nt hall bElon reproduC$d exactly all recolved flom tho per$Oo Of organizalloo originating It. Points of view oroplnions stated " 10 thls dccumont IIro those of tho authors and do not necessarily 111111.25 111111.4- 111111.6 1, , f!prrlSOOI Itlo Q't'Iiclal posltlon orpollcllHl of tht! Natlonallnstltulo of JulStiCO.
Pormills/on to reproduce this Cepilifjhl.d malarial hall boon \)f8nled~ II, FBI Law Enforcement Bulletin MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF SlANDARDS·1963 A 10 the Nntional Criminal JuilUce Rtlfttrooco Servlco (NCJRS).
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National Institute of Justice United States Department of Justice Washington, D. C. 20531
6/B/ B4 . l:1 f f',;( S-S3 ~ORCEMENT rr@~@~i© ~©~@m©@ rBI BULLETIN NOVEMBER 1983. VOLUME 52. NUMBER 11
, Contents Forensic Science " "1 [AcoustiC GYnshot Analysis: The Kennedy "Forensic analysis of Assassination and B~ond (Part II) rc:l S S' .3 By Bruce E. Koenig tape recorded gunshots and other Law Enforcement ili-rFamllY DI~rbance Interven~n 0 ol t" y( transient or impulsive Role ~(, L~rogram I s- sounds. . . has been By Dale Richard Buchanan and Janet M. Hankins an important factor in Crime Problems l~nforcing §nvironmental Laws-A Modern D~ Challenne the disposition of a D L~y William M. Murphy 70< SSS- _ .. number of 'Widely Police-Community 20 Turning the Corner on Racial Violence: The Boston publiciz"~d . . . Relations Experience investigative matters By S. Chuck Wexler and Francis M. Roache in the past 20 years ...." The Legal Digest 23 Investigative Detention and the Drug Courier: Recent Supreme Court Decisions By Jerome O. Cam pane, Jr. By 32 Wanted By the FBI BRUCE E. KOE:NI9 " .. ~:. Special Agent ~"r.u ..", It'.# 61>(1l/.4f,JJ t~f~':\.L,iL,n~ i Technical Services Division Ie Federal Bureau of Investigation Washington, D.C. aoe@1t!JU5ITH=)NO I l
The Cover: Forensic Federal Bureau of Investigation Acoustic Gunshot Analysis Put)l,r,hod by 1110 Office 01 Congrosslonal and acoustic operation':! United States Department of Justice are Important labora. PuhlJc;Alfillr:" Washington, D.C. 20535 Roger S YOlJllrj, Asslslanl ()IIoctor tory procodures which have been Cdllor Thorner; ,J Dcnk"l William H. Webster, Director used In major Ass/S/rml [dl/or Kalluyn r Sulew[,kl The Kennedy Assassination investigations, In· Arl Dirac/or Kevil) J Muillollnnd cludlng the Kennedy Thl' AII'"r,c'y Gann.al /lac, clrlmrMlncJ 1I1,lIlho (l1l1J11r;al,on WI//f''' ['c/tlClr Koron McCarron assass/nallon See I)f ItHlj. pml(JtJlf,IIII'; no{.n~f.inry 1ft Illo trtlf)t,arJrnn nllhn Produc/I()n Managor Jolfrry l Summers article p. 1 PlJlllrc: UU',IIIO',', 10qIJlIO(J lJy lOW of 1110 UUflllllmnnl 01 Heprm/s MarloliUB S, l3Iack and Beyond .Jw~hrrl l)'.o nf ruodlJ felt PfitllltlO ItHf~ pmJocllC,ill hl1', Decm OPpIIlY()(J tJY 1110 Drrm.lnr 01 Iho (JIII( 0 01 Mtlniluomcnl om! Budgol Ihrough Juno a, 19BO (Part I)
ISSN 0014 b6B8 USPS 383 310 --- --~------
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Forensic analysis of tape record The FBI's Forensic Capability ed gunshots and other transient or im The FBI's Signal Analysis Unit in pulsive sounds (i.e. doors slamming, the Engineering Section of the Te~h explosion of fireworks, etc.) has been nlcal Services Division has been In· an important factor in the disposition volved in forensic acoustics, wave· of a number of widely publicized crimi form analysis, ballistics, and electronic nal, civil, and investigative matters in engineering examinations of tape re aural examinations, very high resolu the past 20 years, Including the Kent cordings since the 1950's. Forensic tion waveform analysis, and the pres State University deaths in 1970, the processes Include voice Intelligibility ence or absence of precursor super attempted assassination of President Special Agent Koentg enhancement, authenticity determina· sonic N-waves. Ronald Reagan In 1981, and the tion, spectrographic voice compari The actual number of impulsive in Greensboro, deadly confrontation sons, video enhancement, and copy sounds and their time sequence can N.C., between members of the Ku right comparisons, with analyses of be determined with lower quality re Klux Klan, the Nazi Party, and the tape recorded gunshots and other im \ cordings, even those over telephone Communist Workers Party in 1979. pulsive sounds handled as a signal I lines and transmitting systems, as However, in the last few years, such analysis matter. long as the microphones are not analysis has also been used to dra Under the best recording condi driven beyond their ability to repro matically show and then refute the tions, this signal analysis examination duce very loud sounds. For example, possible involvement of a second can provide an accurate determination a recent shooting incident was ta~e gunman in the assassination of Presi of Which sounds represent gunshots recorded using a police body transmit dent Kennedy In Dallas, Tex., on No and not some other impulsive sound ter system. When played by investig~ vember 22, 1963. (i.e. a door slamming), the number tors, the recording revealed only SIX To allow a better understanding and time sequencing of the gunshots, gunshot-like sounds, whereas physical of the scientific principles involved in the spatial location of where each evidence showed that one individual acoustic gunshot analyses, the tech gunshot occurred, and whether the most forensic recordings of impulsive had fired one shot and the second niques presently used by the FBI to fired projectiles were subsonic or su type sounds are not r7~orded under person fired six shots from his revolv analyze recordings of gunshots and personic. Subsonic projectiles travel the near perfect conditions encoun er for a total of seven gunshots. The other transient sounds will be set at less than and supersonic at greater tered In Greensboro, N.C. . . original tape recording was submitted forth, followed by a rather detailed de A good quality recording and mi than the speed of sound (1130 feet to the FBI to determine the actual scription of the forensic acoustic stue crophone system has to have per second at sea level and 71°F). be~n number of gunshot-like sounds, and If les conducted In the Kennedy assas. used during an incident in order to dif However, matching a particular re possible, who fired the first shot, The sination. This will Include the reports ferentiate between recorded gunshots corded gunshot sound to a specific examination revealed seven gunshot of the House Select Committee on and other impulsive sounds. Record weapon is normally not possible. like sounds using high resolution ~a Assassinations (HSCA), which found a ings over telephones and through For example, in the violent con veform analysis and that shots five 95-percent or better chance of a radio transmitting systems (body, port frontatton In Greensboro, N.C., the and six were only 0.087 second apart. second gunman being involved In the able, and vehicular), or when the gun FBI acoustically examined over 100 This Information, therefore, reflected shooting of President Kennedy; a shot occurs close to the microphone, Impuls!ve-type sounds that had been that the Individual firing the one shot review by the Federal Bureau of In· normally alter tile signal sufficiently to recorded during the Incident by high was responsible for either the fift~ or vestlgatlon refuting that claim: and the prevent a meaningful determination. quality professional equipment. The sixth gunshot In the sequence, sl~ce analysis conducted by the National The actual examination to specify that analysis determined that 39 gunshots tests showed ttl at two consecutive Research Council, which conclusively a sound is a gunshot requires special had been fired, the exact timing se· '\i1I. \ shots could not be fired from that Invalidated the HSCA's result. The de· par quence of the gunshots over 88 sec· ticular weapon In that short a lime- tails of these reports will clearly show onds, which projectiles were sub- and many of the complex problems and span. t' f supersonic, and the physical location , Determining the exact loca Ion 0 thinking Involved In examinations of of each gunshot (usually within ± 3 the source of an Impulsive-type sound recorded gunshots. .• feet) fired by members of the Ku Klux requires a very high quality tape re Klan, the Nazi Party, and the Commu cording made on site, knowledge of nist Workers Party. Unfortunately,
2 I FBI Law Enforcement Bulletin November 1903 I 3 j '! -- --_._.- - l""""'-...... ,..: __ .,."'P', ... _------~------.
"During the past 20 years, [the] murder [of President John F. Kennedy] has prc;>bably ge~erat~d more c~,ntrovet'sy than any other scngle Criminal event In thiS country. Texas School Book DeposItory ------BBN used filters to process the DPD Acoustical Report of Bolt Beranek the approximate location of the micro channel 1 recording during the speci phone, and a scaled map of the area. and Newman fied 5 minutes and displayed this Again, the use of recordings through In an attempt to cover all possi signal in the form of a time-continuous telephone or transmitter systems is ble scientific leads concerning the as waveform. An example of another usually not possible. The examination sassination of President Kennedy, the type of time-continuous waveform is uses the principle that impulsive HSCA asked personnel of Bolt Ber the pattern obtained when an electro sounds reflect and diffract off hard. anek and Newman, Inc. (BBN), in May cardiogram (EKG) displays a person's relatively flat surfaces, like the sides 1978, to conduct an examination of heartbeat. of buildings, in a very predictable two recordings made by the Dallas The waveform display of channel manner. This is analogous to a flash Police Department (DPD) of police 1 had five unique impulsive noise pat light beam reflecting off a mirror in the radio traffic during the assassination. terns thought to be different from mo dark or a bank shot in the game of BBN, a Cambridge, Mass., acoustical torcycle sounds, according to BBN. billiards. These reflections and diffrac firm, was asked to analyze the record Their report reflects that four of these tions result in a waveform that con ings to determine if they contained patterns appeared to be similar to the tains the original impulsive sound fol the sounds of gunfire involved in tl1e characteristics of a gunshot blast with lowed by the echoes off flat surfaces shooting of the President, and if so, a precursor supersonic N-wave. The in the locale. Thus. by carefully meas Evidence submitted to the Tech how many gunshots were recorded other pattern was eliminated as a uring the time delays of the set of nical Services Division for examination and from what locations did the gun possible gunshot since it was different echoes, a unique position can normal must be original recordings and have shots originate. in amplitude and duration. The BBN ly be determined for the original the appropriate supportive material BBN's report 2 of January 1979, report states that a rifle firing a super source of the impulsive sound. This enclosed. to the HSCA reflects that the first re sonic bullet creates two sources of examination is normally ineffective in cording is of DPD radio channel 1, loud impulsive sounds-the muzzle Presldenl and Mrs. Kennedy momenls before Ille doors (due to the very large number Assassination of President which is a continuous recording on a blast and the shock wave of the pro Ifllal shol was fllod. of echoes) and outdoors where few Kennedy Dictabelt of routine police radio traffic. jectile as it travels faster than the horizontal flat surfaces exist (such as On November 22, 1963, Presi The second recording is of auxiliary speed of sound. 4 The shock wave is the middle of a cornfield). dent John Fitzgerald Kennedy was as During the past 20 years, this radio channel 2, which was intermit analogous to a jet fighter producing a Ammunition is designed to be sassinated while riding in a motorcade murder has probably generated more tently recorded on a Gray Audograph sonic boom when it flies faster than either sub- or supersonic when fired through Dealey Plaza in Dallas, Tex. controversy than any other single disc and used by the DPD police offi the speed of sound. These two impul from a particular weapon due to the The alleged assassin, Lee Harvey criminal event in this country. Hun cers assigned to the Presidential mo sive sounds, plus the echoes of these amount and type of gunpOWder, the Oswald, supposedly fired three gun dreds of articles, books. and scientific torcade. 3 However, after a preliminary sounds reflecting and diffracting off shape and weight of the projectile, shots using a rifle while in the Texas reports have been written conr.eming examination, BBN decided to focus :Juch surfaces as the sides of build and other factors. When a supersonic School Book Depository (TSBD) the assassination, covering a wide their attention on the channel 1 re ings. the street, and automobiles, projectile is fired, the bullet will travel Building at the intersection of Elm and range of topics from the significance cording, instead of channel 2, for their result in a particular pattern of sound faster than the speed of sound, and Houston Streets in Dealey Plaza, of bullet fragments found during the analysis. impulse peaks. thus, arrive at the target ahead of the which resulted in the death of our autopsy to who is buried in Oswald's According to BBN, the police However, tests performed by sound of the muzzle blasl. The super 35th President. However, Oswald was grave. However. in recent years, the radio on a DPD motorcycle, which BBN on a radio system similar to that sonic speed of the buliet produces a himself shot and killed soon after the possible existence of another assas could have been in the Presidential used by the DPD showed consider characteristic shock wave, called an assassination and could not be sin in Dealey Plaza, besides Oswald, motorcade, had its transmHting switch able distortion of loud Impulsive N-wave, that appears in the waveform brought to trial. has bec'-''1le a major focus of interest stuck open on channel 1 for approxi sounds such as gunshots, which re as a precursor to the original muzzle in this ongoing controversy. mately 5 minutes during the assassi sulted In the elimination of impulse blast, which itself is then followed by In September 1976, the HSCA of nation. Therefore, the radio micro peaks, change In the position of the echoes. The presence or absence the U.S. House of Representatives, phone would allegedly det~~t. an~ peaks, and even the production of of this N-wave on a high resolution 95th Congress, was authorized a 12· transmit all sounds in the vIcinity 0; new peaks where no impulse peaks waveform shows whether it is super member 1 committee to conduct a the motorcycle, including the noises previously exlsted.5 or subsonic, respectively. complete investigation into the cir produced by the motorcycle itself. Preliminary tests by BBN deter cumstances surrounding the deaths of mined that the four chosen impulse President Kennedy and Dr. Martin patterns occurred at approximately Pl1ologmpils from film SilowlI1g 1110 ass,1sslI1f1110n Luther King, Jr .. including the possibil of Prosldonl I NovomlJor 1US;) I 5 4 I FBI Law Enforcomonl Bullotin ------~------r the same time as the known gunshots significant since the average expected The 88N conclusions were pre in Dealey Plaza and that no other suf number of statistically false matches sented in oral testimony to the HSCA ficiently characteristic patterns were for such a comparison is 13, due to on September 11, 1978, reflecting located in the pertinent 5-minute seg the random noise impulses present that the radio on the DPD motorcycle ment. Also, the time span between throughout the DPD tape. in the Presidential motorcade had re the first and fourth patterns did not 88N then stated that at least 6 of ceived and transmitted the four speci contradict photographic evidence the 15 correlations were false match fied impulse sounds and that each of made during the assassination, the es, because 1 gunshot would have these impulse sounds was possibly a distorted patterns approximated test been fired at the wrong target, 1 gunshot. Due to the false matches patterns of gunshots, and the ampli would have occurred only 1.05 produced by the statistical tec;hnique, tudes of the impulse patterns were in second after earlier correlations, the probabilities, according to 88N, the same general range as test gun which is too fast a firing rate for the that each impulse pattern is a gunshot shots. 6 tested rifle, 3 would have required a are: On August 20, 1978, 88N fired a motorcycle with the open microphone Time 0.0 second-88 percent total of 12 test gunshots with weap to travel at 16 mph, and 1 would have Time 1.6 seconds-88 percent Above: Model of DtJa!ey Plaza showing Ihe roUle of the Presldentia! motorcade. ons located only in the TS8D and on required the motorcycle to travel at 55 Time 7.8 seconds-50 percent the so-called grassy knoll area in mph. The motorcade was thought to Time 8.3 seconds-75 percent Lefl: Photogrsph of re·enactment conducted as Dealey Plaza. Using 36 microphones have been traveling at approximately pari 01 the invesllgalkJoI into the assassinalion. 88N stated that the probability located 18 feet apart on Houston and 11 mph. The remaining nine correla that all four impulse patterns are gun Above lefl: Photograph of the re-enactment Elm Streets, 88N recorded these test tions sufficiently matched the four through a "fie scope from the Texas School Book shots is only 29 percent. 8 gunshot blasts in an effort to recon designated impulse patterns on the " Deposdory. struct acoustically the impulse pat DPD recording to show a DPD micro Acoustical Report of Weiss and The static-like sounds on the terns recorded by the DPD radio phone location varying between 120 Aschkenasy DPD recording could be distorted gun system during the assassination of and 160 feet behind the Presidential shot sounds, since the DPD radio On October 24, 1978, the HSCA President Kennedy. Even though few limousine. Further, the 88N analysis system would have compressed the authorized Mark R. Weiss and Ernest physical changes had been made in found that the four impulse patterns sound of the muzzle blast and its Aschkenasy, Department of Computer Dealey Plaza since 1963, producing may have been gunshots fired as fol strongest echoes, making them only Science, Queens College, City Univer comparable test patterns was very dif lows: slightly louder than the background sity of New York, to conduct an Inde ficult since the impulse patterns on static. For example, if the open micro "1. time 0.0 sec[ond]-one shot pendent anC';lysis of the alleged third the DPD recording were like "badly Dealey Plaza (scale: 1 inch to 10 clicks, whistles, motor noises, sirens phone was on a motorcycle in the from the TS8D. . . gunshot recorded on channel 1 of the smudged fingerprints" due to the feet), a map of Dealey Plaza (scale: 1 and even the sound of a carillon motorcade, most of the weak echoes "2. time 1.6 sec[onds]-one shot DPD radio system to determine with noisy environment In the vicinity of the of a muzzle blast would have been from the TS8D ..• greater accuracy whether it was indic inch to 40 feet) with microphone loca bell. Mostly the recording contains transmitting DPD radio microphone, obscured by the noise of a motorcycle "3. time 7.8 sec[onds]-onfl shot ative of a gunshot from the grassy tions used by 88N In their gunshot re sounds Qenerated during normal the poor quality of the DPD recording engine (which could be the source of from behind the fence on the knoll. construction tests, and aerial and communic~tions on channel 1 of system, and a number of otller prob the continuous noise on channel 1). grassy knoll . . . To conduct their analysis, Weiss ground-level photographs of Dealey the DPD radio dispatching lems. "4. time 8.3 sec[onds]-one shot Thus, the sounds of a gunshot could and Aschkenasy received from the Plaza and the surrounding areas. The system .•.. At a time that the 88N Using the 12 different test gun have been recorded as a sequence of from the TS8D ..." 7 HSCA high quality magnetic tape HSCA also provided them with addi analysis estimates to have been shots from the TS8D and the grassy impulse sounds (the muzzle blast and copies of the DPD recording, a high tional information, such as building about 12:28 p.m., a microphone on knoll and the 36 different microphone its echoes), only a few having a larger quality tape copy of the gunshot heights in Dealey Plaza, distances not a mobile unit apparently became locations used by 88N, a total of 432 amplitude than the engine noise and sounds recorded by 8BN during the shown on the maps, the location of stuck in the 'on' position and began gunshot patterns were recorded none of which would have sounded acoustical reconstruction tests per shooters during the 88N reconstruc to transmit a continuous noise that (12x36=432). These 432 test gun like gunshots after being changed by formed In Degley Plaza on August 20, tion experiment, and the air tempera is believed to be the sound of a shot patterns were then compared to ture during the assassination and re motorcycle engine." 9 the circuitry of the DPD radio and re 1978, a topogl'~phlcal survey map of the Impulse patterns Isolated on the construction experiment. cording equipment. channel 1 DPD recording using a sta Weiss and Aschkenasy's report The report states that the higher tistical analysis technique. This com states: Impulse sounds on the DPD recording pariljon provided a total of 15 possible "The DPD recording contains a could be generated by a number of matches, which was not particularly wide range of sounds-speech, 6 I FBI Law Enforcement Bulletin _, November 1983 I 7 .~~------~------. -- - ,.. I .' :1 '"r sources, including misfiring of a mo environment, with a number of Using the topographical map of tern on the DPD recording, the errors "2. The microphone that picked up performed by both BBN and Weiss torcycle engine, noise produced by randomly spaced echo-producing Dealey Plaza and the BBN recon in the speed of sound determination the sounds of the probable gunshot and Aschkenasy that there were gun the motorcycle's ignition system, radio structures, it is possible to see that struction results (test gunshots fired and the time accuracy of the DPD re was on Elm Street and was moving shots in Dealey Plaza from both the on-and-off clicks, scratches on the the pattern of sounds a listener will only from the TSBD and the grassy cording had to be determined. Weiss at a speed of about 11 miles per TSBD building (where Lee Harvey Dictabelt, and electrical or mechanical hear will be complex and unique for knoll), Weiss and Aschkenasy at and Aschkenasy used a ± 1.0-percent hour in the same direction as the Oswald allegedly fired three gunshots) disturbances in the system. Weiss and any given pair of gun and listener tempted to predict a pairing of a error for the speed of sound due to motorcade. At the time the probable and the grassy knoll area (one gun Aschkenasy, in an effort to differenti locations. For example, assuming a shooter and a microphone that would temperature variations (±10· F) and a gunshot was fired, the microphone shot) during the assassination of ate these sounds from a gunshot, as fixed location of a listener, the produce a sound pattern that would -4.0-percent to -6,0-percent error was at a point about 97 feet south President Kennedy, the HSCA found, serted that the most effective and echoes that he hears and the times match the specified impulse pattern of for speed variations on the DPD Dic of the TSBD and about 27 east of in part, that "scientific acoustical evi most reliable characteristic to deter at which he hears them will be the DPD recording. To calculate these tabelt recorder, since the average the southwest corner of the dence establishes a high probability mine if a sound is a gunshot is the related uniquely to the location of predicted echo patterns of a particular speed of the recorder over a 15- building, (For both distances, the that two gunmen fired at President presence or absence of echoes from the gun, since for each different shooter and microphone location in minute segment was 5.0 percent too uncertainty is about ± 1 foot). John F. Kennedy." 15 the muzzle blast. These echoes are location of the gun, even though Dealey Plaza, three pieces of informa slow. These two errors combined to "3. The probable gunshot was fired Having considered in part I the the result of firing a gun, which pro thEl distances from the listener to tion were needed: give a maximum possible time error from a point along the east-west analyses of BBN and Weiss and duces a loud impulse sound that the various echo-producing objects "(1) Which objects in Dealey Plaza range of -3.0 percent to -7.0 per line of the wooden stoc~ade fence Aschkenasy of recorded sounds relat spreads out and is heard in every di are the same, the distances from would produce echoes in the region cent. Weiss and Aschkenasy then on the grassy knoll, about 8 feet (± ing to the assassination of President rection. This sound is then r"flected these objects to each gun location of interest on Elm Street for a gun stated that since any value within this 5 feet) west of the corner of the John F. Kennedy, the conclusion will and diffracted off any structures in the are different. Consequently, the fired from the vicinity of the grassy maximum error range is valid, it was fence." 13 report on a review and the findings of area, producing echoes which arrive times at which the echoes are knoll; (2) how far these objects possible to choose a value that cre In his testimony in the public the Federal Bureau of Investigation at the microphone later than the heard will be different for each were from the locations of the gun ated the best match between the al hearing before the HSCA on Decem and the analysis conducted by the direct muzzle blast impulse. Weiss location of the gun. Similarly, and of the microphone; and (3) leged gunshot impulse and predicted ber 29, 1978, Weiss mentioned two National Research Council. FBI echo sequences. A - 4 ,3-percent and Aschkenasy contended that the assuming a fixed location of the what was the speed of sound under additional findings that were not in his (Continued next mon, I specified impulse pattern on the DPD gun, any change in the location of the conditions for which tile echo error factor was picked since it gave report of February 1979, Weiss stated recording had these echoes, thus re the listener will change the travel times were to be the best match. that the specified pattern found to be FOOlnotes , The members ware Louis Stokes-Chairman flecting that it was a gunshot. Howev distances between him and the predicted." 12 Weiss and Aschkenasy, using a a gunshot from the grassy knoll was statistical technique and by physically (Ohio), Richardson Preyer (North Carolina), Waiter E. er, in public testimony before the echo-producing structures, and thus First, the topographical map re most likely supersonic and fired by a Fauntroy (District ot Columbia), Yvonne Brathwaite Burke Committee on December 29, 1978, measuring on the topographical map (California), Christopher J. Dodd (Connecticut), Harold E. the timing of the pattern of sounds vealed many of the reflecting and dif rifle. However, in their report, Weiss Ford (Tennessee), Ftoyd J. Fithian (Indiana), Robert W. of Dealey Plaza with string, deter Weiss stated that it Is " ..• not so he hears. If the listener is in motion fracting surfaces within Dealey Plaza. and Aschenasy stated they did not Edgar (Pennsylvania), Samuel L. Devine (Ohio), Stewart mined that the specified impulse pat B. McKinney (Connecticut), Charles Thono (Nebraska). much the echo pattern as the evi as the muzzle blast and the various Second, direct measurement on the know the type of gun used. Weiss and Harold S. Sawyer (Michigan). tern on the DPD recording of channel 'Appendix to Heanngs Before the Select Committeo dence of a supersonic shock wave" echo sounds reach him, the times map determined the distances from also testified that the weapon fired 1 was "a sound as loud as a gunshot on AssaSSinations, U.S. House 01 Representatives, that would characterize a gunshot at which he hears the muzzle blast the gun to the reflecting and diffracting from the grassy knoll was aimed in 95th Cong., 2d Sess., Volume VIII, Washington, D.C., sound and eliminate other sounds like and its echoes will be related from the grassy knoll" area of Dealey the general direction of President 1979, pp. 4 t -42 surfaces and then to the microphone , Diclabells and Gray Audograph discs were used Plaza, with a probability of 95 percent the backfire of a motorcycle. Weiss uniquely to his location when he location, Third, the speed of sound was Kennedy's limousine. with early dictating equipment to record Voice further stated he does not know of or higher. Information; a styl~s imprinted groovos on thoir plastic hears each sound, determined to be approximately 1,123 Aschkenasy stated at that public surfaces, much like a poor quality phonograph rocord, The complete findings of Weiss any other sound that might resemble "The 'listener' that we have feet per second, principally by using hearing that he Was so sure of their which could then be played back at a later lime. the pattern he determined to be a and Aschkenasy concerning the spe • Appendix, pp. 41-43, 52-55. discussed, of course, could be the known air temperature near Dealey results that "if someone were to tell • Appendix, pp. 76-77. cific sounds on the DPD recordings gunshot due to the presence of the either a human ear or a Plaza on November' 22, 1963, of ap me that the motorcycle was not in • Appendix. pp. 43-45. supersonic shock wave and the are: Dealey Plaza, and he was, In fact, I Appendix, p. 46. microphone, If a microphone proximately 65· F (the speed of sound • Appendix, pp. 47-46. muzzle blast impulses. 'o It is not receives the sounds and they are varies with changes in air tempera "1, The recording very probably somewhere else, and he was trans • Appendix, p. 11. known which characterisiic Weiss and contains the sound of a gunshot mitting from another location , , , I 10 Broadcast of public hearing over radiO station subsequently recorded, the ture). WETA-f'M In Washington, D.C. Aschkenasy actually used in their recording becomes a picture of the that was fired from the grassy knoll. would ask to be told where that loca To make a comparison of predict 11 Appendix, p. 7. analysis, The probability of this event is tion is, and once told where It is, I event, not unlike a 'fingerprint,' that ed echo patterns to the specified pat- " AppendiX, p. 19. In their report to the House permanently characterizes the computed to be at least 95 percent. would go there, and one thing I would U Appendix, p, 10. Select Committee on ;\ssassinations, ,. Supra note 10. original gun and microphone expect to find is a replica of Dealey " Report 01 the Se/ecf Commillee on ASSBssinlltk:ms, Weiss and Aschkenasy stated: locations," II Plaza at that location. That's the only US HOllse of Reprosontatives. Fmdmgs and Recommen· dallons, 951h Cong., 2d S055 .• U.S. Governmont Printing "If we now assume that the sound way that It can come out," 14 Based Ollice, Washington, D.C., 1979, p. 58. source [the gun] and the listener primarily on the acoustical analyses are located in a typical urban 8 I FBI Law Enforcement Bulletin November 1963 I 9 ---="","- \ I , \ i ! I,, , , 1 \ --'-"...--~---::' ' ... , . 'L: