This 17 March post from internal NSA newsletter SIDToday describes analysis of a new video from Al Qaeda leader Ayman al-Zawahiri, allowing for near-perfect voice matching. In 2006, NSA was considering a hand-held voice recognizer for use in “detention centers and guard posts in conflict regions”: see the Intercept article 328 NSA Documents Reveal “Vast Network” of Iranian Agents, Details of a Key Intelligence Coup, and a Fervor for Voice-Matching Technology, 15 August 2015.
This 3 February 2006 article from NSA newsletter SIDToday describes how the agency’s analysis of a video statement by Ayman al-Zawahiri broadcast by Al-Jazeera confirmed that the voice matched the Al Qaeda leader’s previous recordings. The analyst states that the video shows that al-Zawahiri had undergone a medical procedure for a “possible aneurysm in his forehead”: see the Intercept article 328 NSA Documents Reveal “Vast Network” of Iranian Agents, Details of a Key Intelligence Coup, and a Fervor for Voice-Matching Technology, 15 August 2015.
This January 2006 post from the NSA internal newsletter SIDToday describes advances in voice-recognition technology, which is helping the agency identify the speakers on intercepted Al-Qaeda recordings. The agency is also developing the technology, which can identify a voice speaking multiple languages, to support its emerging Insider Threat Program: see the Intercept article Finding Your Voice, 19 January 2018.