US 9203972

An analysis of U.S. Patent No. 9,203,972 reveals the following details regarding its origin, ownership, and the technological advancements it protects.

Title: Efficient audio signal processing in the sub-band regime

Assignee: The current assignee of record is Cerence Operating Co. The original assignee was Nuance Communications Inc.

Inventors: Gerhard Uwe Schmidt, Hans-Jörg Köpf, and Günther Wirsching.

Filing Date: September 14, 2012

Issue Date: December 1, 2015

Abstract:
The patent describes a signal processing system designed to enhance an audio signal. The method involves dividing the audio signal into multiple audio sub-band signals. A portion of these sub-band signals is then excised, or removed. The remaining sub-band signals are processed to create enhanced versions. Following this, at least some of the previously excised sub-band signals are reconstructed. Finally, these reconstructed sub-band signals are combined with the enhanced sub-band signals to generate a final, enhanced audio signal.

Overview of Independent Claims:

This patent has five independent claims which outline the core novelties of the invention.

Claim 1 details a method for audio signal processing. This method involves:

• Dividing a signal from a microphone into several "microphone sub-band signals."
• Removing a predetermined number of these sub-band signals.
• Processing the remaining sub-band signals to reduce noise or echo, resulting in "enhanced microphone sub-band signals."
• Reconstructing the sub-band signals that were initially removed, using the enhanced signals.
• A key part of the noise/echo attenuation process involves using a "reference signal" which is also divided into sub-bands, with a corresponding number of sub-bands excised. An echo compensation filter is then adjusted based on the remaining reference sub-band signals and used to filter the remaining microphone sub-band signals.

Claim 5 describes a similar method of audio signal processing with a specific focus on the reconstruction step. In this claim, the reconstruction of an excised microphone sub-band signal is achieved by averaging the remaining microphone sub-band signals that are adjacent in time to the one that was removed.

Claim 6 also outlines a method for audio signal processing, but with a different reconstruction technique. Here, the excised microphone sub-band signals from a specific point in time are reconstructed through interpolation. This interpolation uses the remaining microphone sub-band signals from that same moment in time as well as those from adjacent moments in time.

Claim 8 shifts focus from the method to the signal processing system itself. It describes a system comprising:

• An "analysis filter bank" to divide the audio signal into sub-bands.
• A "first filter" to remove a subset of these sub-band signals.
• A "second filter" to process the remaining sub-band signals into enhanced versions.
• A "processor" to reconstruct at least some of the removed sub-band signals.
• A "synthesis filter bank" to combine the reconstructed and enhanced signals into a final enhanced audio signal.
• The novelty in this claim lies in the processor's function, which involves averaging two signals from the enhanced audio sub-band signals to create a replacement for one of the excised signals.

Claim 12 describes a signal processing system similar to that in Claim 8. However, the unique aspect of this claim is the processor's method for reconstruction. It reconstructs excised audio sub-band signals from a particular time by interpolating the remaining sub-band signals from that same time and adjacent times.

Claim 13 describes another variation of the signal processing system. The key feature of this claim is the "second filter," which is an echo compensation filter. The system also includes components to process a reference signal in a similar manner to the primary audio signal (dividing it into sub-bands and excising a subset). The echo compensation filter is adapted based on the remaining reference sub-band signals and then used to remove echo from the remaining audio sub-band signals.

As of today's date, May 8, 2026, a search of the CAFC dockets for 2026 did not yield any public records of litigation involving US Patent 9,203,972. However, this does not definitively mean no litigation exists, as some records may not be publicly accessible or indexed in the manner searched.