Invalidity dossier
US 6973574
Recognizer of audio-content in digital signals
Current assignee: Microsoft Technology Licensing LLC
Added 9/23/2026, 4:12:51 PM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 6973574 B2
Title: Recognizer of audio-content in digital signals
Patent number / application: US 6973574 B2; application US09/843,254, filed 2001-04-24.
Inventors: M. Kivanc Mihcak and Ramarathnam Venkatesan.
Assignee: Original assignee [Microsoft Corp.](/litigations/by-plaintiff/Microsoft%20Corp.); current assignee listed as Microsoft Technology Licensing LLC. A 2014-12-09 reassignment to Microsoft Technology Licensing, LLC is recorded.
Key dates from the supplied text: Priority date 2001-04-24; publication of US20020184505A1 on 2002-12-05; patent granted/publication of US6973574B2 on 2005-12-06; legal status "Expired – Fee Related," with adjusted expiration 2024-01-22.
Purpose: The patent addresses recognition of the audio content of digital signals. The background explains that digital audio clips are widely distributed, and that hashing techniques—mapping large blocks of data to small structured identifiers ("hash values")—are a proposed approach to audio clip indexing and copyright protection. A stated concern is that a good audio hashing technique should yield the same identifier despite alterations that are perceptually similar to a human listener, while producing a different hash value when changes are audibly different. The text also notes that semantic categorization of audio content previously required subjective human analysis, with no automated technique existing.
Plain-language scope: The described technology determines one or more hash values for the original audio content of a digital signal. An "identification hash value" uniquely identifies the original content and helps determine whether another signal's content is substantially perceptually the same, supporting identification and copyright-related uses. A "categorization hash value" groups original content with other audio works having similar hash values, enabling semantic classification of audio works into categories. Figures describe an MCLT transform, time-frequency representations, significance maps, a statistic estimator, and flow-diagram methodological implementations.
Source: https://patents.google.com/patent/US6973574/en
What the excerpt does not establish: The supplied text omits the claims, detailed description, and references, so specific claim scope, limitations, and prior art are not verifiable here. It also does not establish litigation, validity, or the accuracy of the listed legal status or assignees (the source itself notes such listing is not a legal conclusion).
Generated 10/1/2026, 9:51:03 PM
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Litigation summary
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PTAB challenges
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Assignment history
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Prior art
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Obviousness
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Extensions
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Derivative works
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