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Forensic Acoustics
the University of Illinois at Urbana-Champaign, all in Elec-
Maher, R. C. (2007). Acoustical characterization of gunshots. Proceedings 1958): “Current advances in the technology of electronics
of acoustical events, and educate the attorneys, defendants,
of the IEEE SAFE Workshop on Signal Processing Applications for Public
trical Engineering. His professional interests are in digital
judges, and juries about the meaning, significance, and limi-
and sound recordings make inevitable their increased use
audio signal processing, audio forensic analysis, music syn-
Security and Forensics, Washington, DC, April 11-13, 2007, pp. 1-5.
to obtain and preserve evidence possessing genuine proba-
tations of the recorded evidence (Audio Engineering Soci-
Maher, R. C. (2009). Audio forensic examination: Authenticity, enhance- ment, and interpretation. IEEE Signal Processing Magazine 26, 84-94.
thesis, and acoustics. He is a Fellow of the Audio Engineer-
ety, 1996; Maher, 2009). Figure 2 depicts an interpretive an- ing Society, a Senior Member of the IEEE, and for 31 years, a
tive value. Courts should deal with this class of evidence in
notation that has been added to a time waveform to assist
Maher, R. C. (2010). Overview of audio forensics. In: Sencar, H. T., Velastin,
member of the Acoustical Society of America.
S., Nikolaidis, N., and Lian, S. (eds), Intelligent Multimedia Analysis for Se- of this scientific development. Safeguards against fraud or
with an investigation.
curity Applications. Springer-Verlag, Berlin, pp. 127-144.
oMtchGeirntayb, uT.seJ. a(r2e01p5r).ovWidhyedthbe yCjuydahicoigal CinousinsttyenPrcoesetchuatotr’as Oprffiocpe eIrs
Forensic Acoustics and the US Courts
Spending Half a Million Dollars on Dash Cams for Cleveland Police Cars.
Audio forensics traces its origins to the development of por-
Available at Accessed May 27, 2015. McKnight, J. G., and Weiss, M. R. (1976). Flutter analysis for identifying
ing the admissibility of audio forensic evidence is United
An overview. Proceedings of the Audio Engineering Society 54th Interna- States v. McKeever (1958). In the McKeever case, two de-
(FBI) laboratories have developed techniques and proce-
tional Conference: Audio Forensics, London, UK, June 12-14, 2014.
fBeonltd, Ran. Hts.,wCeoorepeirn, Fd.iSc.,teDdavfiod,rEe.xEt.,oDrteinoens, Pin. Ba.,nPiacknetitr, aJ.cMke.,taenedriSnteg-
National Transportation Safety Board. (2007). Cockpit Voice Recorder dures for assessing the authenticity and audible contents of
vens, K. N. (1970). Speaker identification by speech spectrograms: A sci-
Handbook for Aviation Accident Investigations. Vehicle Recorder Division, foOrffiencesiocf RaeusdeairochreancdorEdnigningeseroinbgtanindeOdffifcreoomf AlvaiawtioennSfaofertcye, mWaesnht-
prosecution involving the International Longshoremen’s
ington, DC. Available at Accessed May
entist's view of its reliability for legal purposes. Journal of the Acoustical Association. After his indictment, the defendant McKeev-
investigations, and similar capability has been instituted
Society of America 47, 597-612.
er had arranged to make a surreptitious tape recording of
27, 2015.
Byrne, G. (2002). Flight 427: Anatomy of an Air Disaster. Springer Science+Business Media, New York.
National Transportation Safety Board. (2015). Cockpit Voice Record-
a conversation he had with an individual who later was a
the world (Koenig, 1990). As described in Modern Audio ers and Flight Data Recorders. Available at
Cooper, A. J. (2008). The electric network frequency (ENF) as an aid to au-
Fcovre-fndsri. cAsc:cDesisgeditMalay“G27o, 2o01d5”. and Digital “Bad,” tenet 3, Nixon Presidential Library and Museum. (2015). History of the White
witness in the trial. During the trial, McKeever’s defense
thenticating forensic digital audio recordings – An automated approach.
thenticity determination, has become more difficult in our
team sought to challenge under cross-examination the wit-
House Tapes. Available at Accessed May era of read/write digital recording and computer processing
Proceedings of the Audio Engineering Society 33rd International Conference:
nAeussd’ioteFsotriemnsiocsn–yThbyeoprylaynidnPgractpicoe,rDtieonnvero, fCtOh,eJucnlea5n-d7,e2s0t0in8.e tape
27, 2015.—stBoorsitconreBloiamnbceres.oPnubplhicyBsircoadl caanstainloggSemrvaicge-,
Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993). Supreme Court of the recording to refresh the witness’ recollection. The court al-
broadcast aired May 29, 2013. Available at
United States, 509 U.S. 579 (1993), No. 92-102. Available at http://laws.
netic tapes.
lowed the tape to be played but only via headphones so that
ers. Accessed May 27, 2015.
Perlin, M. W. (2010). Explaining the likelihood ratio in DNA mixture inter- Accessed May 27, 2015.
the witness could hear it but not the jury. When the defense
Grigoras, C. (2005). Digital audio recording analysis: The electric network thfrenquesnocuyg(hENt Fto) chritaevrieont.hIenterrencaotirodnainl Jgouprnlayl eofdSpineeccho, Luarntgusaogethanadt
Forensic Acoustics and Watergate
the Law 12, 63-76.
the jury also could hear it, the prosecution objected to the
on Human Identification, San Antonio, TX, October 11-14, 2010.
tPioczsa,iFn., atnhdeBUegnaiutlet,dDS. Rta. t(e20s0o5)c.cVuoricreide1n5tifiyceataiorns anftdeerlimMincaKtieoenvuesr-
Koenig, B. E. (1990). Authentication of forensic audio recordings. Journal of use of the tape because its admissibility as evidence had not
ing aural-spectrographic protocols. Proceedings of the Audio Engineering during the Watergate scandal. In 1971, late in his first term
the Audio Engineering Society 38, 3-33.
been established. Specifically, the court had to address the
Society 26th International Conference: Audio Forensics in the Digital Age, in office, President Richard Nixon directed the Secret Ser-
Koenig, B. E., and Lacey, D. S. (2014). Forensic authenticity analyses of the metadata in re-encoded WAV files. Proceedings of the Audio Engineering
Denver, CO, July 7-9, 2005.
fact that the recording was obtained secretly out of court, the
vice to install audiotaping systems in the Oval Office and
Society 54th International Conference: Audio Forensics, London, UK, June participants were not sworn, the witnesses disputed whether
Stearman, R. O., Schulze, G. H., and Rohre, S. M. (1997). Aircraft damage thdeteCctaiobninfreotmRaocoumsticoafndthneoiWse himitpereHsseodusiegn, ailns fothunedpbryeasicdoecnkpt’ist
12-14, 2014.
or not they recognized even their own voices, and the legal
voice recorder. Proceedings of the National Conference on Noise Control private office in the Executive Office Building (EOB) next
Koenig, B. E., Lacey, D. S., and Killion, S. A. (2007). Forensic enhancement chofadinigiotafl caudsitordeycohrdaidngns.oJotubrneaelnofdtehme AoundsiotrEantegidneteorinegnSsoucrietya5d5-,
Engineering 1, 513-518.
to the White House, and at Camp David, the president’s re- United States v. McKeever. (1958). United States District Court in the South-
missibility of the audio evidence.
ber of prior federal court rulings, then established what the forensic acoustics community now refers to as the Seven Tenets of Audio Authenticity (United States v. McKeever,
treat in rural Maryland. The existence of these recording
Lindley, D. V. (2014). Understanding Uncertainty. John Wiley & Sons, ThHoebcookeunr,tNeJx.aminedthesequestionsandconsideredanum-
ern District of New York, 169 F. Supp. 426 (S.D.N.Y. 1958). Available at syhsttpe:/m/tisnywural.scokmn/oqhwgntlqno.nAlcycetsosedaMsaeyle2c7t, 2g01ro5.up of individuals
30 | Acoustics Today | Spring 2020, Special Issue
Summer 2015 | Acoustics Today | 29
24 | Acoustics Today | Summer 2015 Reprinted from volume 11, issue 3
a manner that will make available to litigants the benefits
foundation for such proof be laid.”
  Advisory Panel on White House Tapes. (1974). The EOB Tape of June 20, table recording equipment, and examples of the use of audio
[...]“A review of the authorities leads to the conclusion that,
1972. US District Court for the District of Columbia.
rAelecxoarndienr,gAs.i, nFoUrtSh,cOo.u, arntsd dTautnesttaoll,tDh.e(m201id2)-.1M95us0isc.aAndltnhoisuegfihntghere-
tape recorders. Journal of the Audio Engineering Society 24, 728-734. before a sound recording is admitted into evidence, a foun- Moore, A. H., Brookes, M., and Naylor, P. A. (2014). Room identification
printing and reference cancellation applied to forensic audio enhance-
using roomprints. Proceedings of the Audio Engineering Society 54th Inter-
courts generally began to accept the unique importance of
(1n)attiohnatl Cthoenferrecnocer:dAiundgiodFeovreincseicws, Laosncdaopna, bUlKe, oJufntea1k2i-n14g, t2h01e4c. on-
ment. Proceedings of the Audio Engineering Society 46th International Con- audio recordings, especially in cases involving speech ob- ference: Audio Forensics - Recording, Recovery Analysis, and Interpretation,
Morrison, G. S. (2011). Measuring the validity and reliability of forensic
tained via clandestine surveillance or wiretaps, there were
versation now offered in evidence; (2) that the operator of
Denver, CO, June 14-16, 2012.
sAiugdnioifiEcnagninteecroinngsSiodceiertayt.i(o1n99s6)r. eAgEaSr2d7-i1n9g96:thAeESFRoecuormthmenAdmedePnradc-
likelihood-ratio systems. Science & Justice 51, 91-98.
the device was competent to operate the device; (3) that the Musialik, C., and Hatje, U. (2005). Frequency-domain processors for effi-
tice for Forensic Purposes — Managing Recorded Audio Materials Intended
cient removal of noise and unwanted audio events. Proceedings of the Au- tidoionsEnogrindeerlientgioSoncsiethya2v6ethnIonterbneaetinonmal aCdonefeirnentche:eAruedcio rFdoirnengs;ic(s5in)
ment’s protections against unreasonable searches and sei-
for Examination. Audio Engineering Society, New York.
zures and concern about the legal admissibility of a record-
the Digital Age, Denver, CO, July 7-9, 2005.
that the recording has been preserved in a manner that is
Audio Engineering Society. (2000). AES43-2000: AES Standard for Forensic ing as being a bona fide representation of the sonic events
National Academy of Sciences. (1979). On the Theory and Practice of Voice shown to the court; (6) that the speakers are identified; and
Purposes — Criteria for the Authentication of Analog Audio Tape Record- ings. Audio Engineering Society, New York.
Identification. National Academies Press, Washington, DC. (N7a)tiothnaltAtchaedecmoynovfeSrcsiaenticoesn.(e1l9i8c2i)t.eRdepworatsofmthaedCeomvomliuttneetaornilByalalinstdic
actually present during the recording process.
Beck, S. D., Nakasone, H., and Marr, K. W. (2011). Variations in recorded ThaceouMsticKguenesvheort Cwavseeforms generated by small firearms. Journal of the
Acoustics. National Academies Press, Washington, DC.
in good faith, without any kind of inducement.”
Acoustical Society of America 129, 1748- 1759.
Among the key cases in the US federal court system regard-
National Academy of Sciences. (2009). Strengthening Forensic Science in the United States: A Path Forward. National Academies Press, Washington,
Begault, D. R., Heise, H. D., and Peltier, C. A. (2014). Forensic musicology:
Since the early 1960s, US Federal Bureau of Investigation
dation must be established by showing the following facts:
recording is authentic and correct; (4) that changes, addi-
in other public and private forensic acoustics labs around
pretation. Proceedings of Promega’s Twenty-First International Symposium A significant turning point in the practice of forensic acous-
and to the Secret Service (Nixon Presidential Library and Museum, 2015). President Nixon presumably assumed that the recording system's existence would be of interest to no
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