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(S) Technology that Identifies People by the Sound of Their Voices
FROM: Adolf Cusmariu
Technical Director, Content Analysis Services (S21212)
Run Date: 01/04/2006

(S//SI) "I'd know that voice anywhere..." When SIGINT transcribers work the same target set
for a long time, they sometimes can identify a certain individual in recorded conversations, just
by the sound of his voice and by his unique way of speaking. This process was traditionally
known as "voice identification." Now, rapidly improving technology is available that can do the
same job mathematically, and with it come new opportunities for the Intelligence Community.
Indeed, such methods have proven surprisingly more robust and consistent than humans;
refinements and improvements do continue, mainly to reduce errors and dependence on
communications channels.
(S//SI) As an example of what this new "voice-matching technology" can do, state-of-the-art
software and mathematical analysis verified voice intercepts from leaders of Al-Qaida. It
matched speakers from various SIGINT intercepts and confirmed that certain in-theater
detainees were not those suspected of terrorist activities.
(TS//SI) One specific accomplishment involved a request for an urgent voice comparison of
terrorist Abu Hakim with an individual interrogated by the FBI in Iraq. Technical analysis
showed there was no statistical reason to believe the two voices matched, a conclusion fully
confirmed by a native-speaking linguist. Subsequently, the FBI arrested the individual in
question based on other incriminating evidence.
(S//SI) However, transmissions by Arab broadcasters of Al-Qaida's second-in-command, Aiman
Al-Zawahiri , showed an excellent acoustical match. Other analyses determined that the voice
of Usama Bin Laden is unmistakable and remarkably consistent across several transmissions.
During Operation IRAQI FREEDOM, it was determined that the voice claimed to be of deposed
leader Saddam Hussein was indeed his, contrary to prevalent beliefs.
(TS//SI) In addition to supporting the Counterterrorism effort, voice-matching technologies are
being applied to the emerging Insider Threat initiative , an attempt to catch the "spy among
us." As a test, analysts mathematically compared old intercepts and audio files of NSA spy, Ron
Pelton , who was recorded while contacting the Soviet embassy. Those comparisons showed
excellent correlation. Had such technologies been available twenty years ago, early detection
and apprehension could have been possible, reducing the considerable damage Pelton did to
national security.
(S) Furthermore, mathematical vocal tract modeling can even identify voices largely
independently of the language spoken. For example, a request from a customer within
NSA's Counterintelligence structure posed the challenge of matching voices of a Chinese person
conversing in English with two external contacts. Despite the phonetic irregularities in
articulation that virtually all non-native speakers make, mathematical analysis showed
nevertheless that the voices indeed match with a very high degree of confidence. Furthermore,
comparison with an audio file where the person spoke Chinese with a cohort once again proved a
high-confidence match.
(S) The voice-matching technology was developed by MIT/Lincoln Labs under NSA contract. It is
used by S21212 in support of automated speaker identification services for a wide variety of
offices within the Agency. It is also rapidly becoming the standard in the Intelligence
Community.
POC: Adolf Cusmariu, S21212, Technical Director,

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DERIVED FROM: NSA/CSSM 1-52, DATED 08 JAN 2007 DECLASSIFY ON: 20320108