Prior art — US Patent 11798576

Analysis of Prior Art for U.S. Patent 11,798,576

An analysis of the prior art cited during the prosecution of U.S. Patent 11,798,576, "Methods and apparatus for adaptive gain control in a communication system," reveals several key patents that inform the landscape of the invention. This analysis examines the most relevant of these citations, their core teachings, and their potential relationship to the claims of the '576 patent. The following references were considered material by the USPTO examiner in determining the patentability of the invention.

U.S. Patent 9,124,234 B1

Full Citation: US 9,124,234 B1
Title: Method and apparatus for adaptive automatic gain control
Assignee: Entropic Communications, LLC.
Filing Date: April 11, 2014
Publication Date: September 1, 2015
Brief Description: This patent details a method for adaptive automatic gain control (AGC) that adjusts its parameters based on the characteristics of an input signal. It describes a system that measures signal power and adjusts gain, but also adapts the attack and decay rates of the AGC based on whether the signal contains transient spikes or more continuous content. This allows for a more nuanced gain adjustment that can react quickly to sudden changes without being overly aggressive during normal speech.
Potential Anticipation: This reference is relevant to the general concept of adaptive gain control. However, it does not explicitly teach the core novelty of the '576 patent's independent claims (1, 12, and 18), which is the use of a target SNR range at a specific listener position to drive the gain adjustments. The '234 patent is more focused on adapting the AGC's temporal characteristics (attack/decay) based on signal power dynamics rather than maintaining a specific SNR for a listener. Therefore, while it shares the concept of adaptive gain, it would likely not be seen as anticipating the specific method of using a minimum and maximum SNR threshold at a listener's position to control the gain increment and decrement.

U.S. Patent Application Publication 2013/0179163 A1

Full Citation: US 2013/0179163 A1
Title: In-car communication system for multiple acoustic zones
Inventor: Tobias Herbig (also an inventor on the '576 patent)
Filing Date: January 10, 2012
Publication Date: July 11, 2013
Brief Description: This application describes an in-car communication system designed to manage audio in multiple acoustic zones within a vehicle (e.g., front and rear seats). It focuses on preventing feedback and ensuring clear communication between these zones. It discusses adjusting signal processing parameters based on which zone is active, but its primary focus is on managing the spatial aspects of in-car audio and preventing echo and feedback between different speaker/microphone pairs.
Potential Anticipation: This reference, although involving the same field and one of the same inventors, does not appear to anticipate the key elements of the '576 patent's claims. Its focus is on multi-zone management rather than the specific gain control logic detailed in claim 1. It does not teach the concept of defining a target SNR range and dynamically adjusting an actual gain to meet a target gain based on whether the current SNR is above or below that range. The '163 application is more concerned with routing and echo cancellation in a multi-zone environment.

U.S. Patent Application Publication 2010/0202631 A1

Full Citation: US 2010/0202631 A1
Title: Adjusting Dynamic Range for Audio Reproduction
Inventor: William R. Short
Filing Date: February 6, 2009
Publication Date: August 12, 2010
Brief Description: This publication discloses a system for adjusting the dynamic range of an audio signal based on the ambient noise level. The system estimates the noise floor and adjusts the audio signal to ensure it remains audible above the noise. The goal is to make quiet parts of the audio louder in a noisy environment while preventing loud parts from becoming overwhelming.
Potential Anticipation: This reference is relevant as it adjusts audio based on noise. However, it differs from the '576 patent in a crucial way. The '631 application adjusts the dynamic range of the audio signal itself, compressing it to fit within a certain audibility window above the noise floor. The '576 patent, in contrast, applies a gain to the overall signal with the specific goal of keeping the Signal-to-Noise Ratio (SNR) within a predefined range. It does not explicitly mention dynamic range compression. The method of comparing an actual gain to a target gain and incrementing or decrementing based on SNR thresholds is a more specific implementation not detailed in the '631 application.

U.S. Patent Application Publication 2010/0035663 A1

Full Citation: US 2010/0035663 A1
Title: Hands-Free Telephony and In-Vehicle Communication
Assignee: Nuance Communications, Inc. (a predecessor in interest to the '576 patent's assignee)
Filing Date: August 7, 2008
Publication Date: February 11, 2010
Brief Description: This application describes a system that integrates hands-free telephony with in-vehicle communication. It discusses using beamforming microphones to focus on a speaker and noise suppression techniques to improve signal clarity. It mentions adjusting volume levels but focuses more on the seamless switching between external calls and internal vehicle communication.
Potential Anticipation: While this application operates in the same technical space, its inventive focus is on the integration of different communication modes. It does not describe the specific adaptive gain control mechanism that is the cornerstone of the '576 patent's claims. The detailed process of determining speech and noise levels, calculating an SNR, and using an actual-versus-target gain adjustment to maintain that SNR within a specified range is absent from this disclosure.

In summary, while the cited prior art references address various aspects of audio signal processing, noise reduction, and automatic gain control within communication systems, none appear to fully anticipate the specific combination of elements claimed in the independent claims of US 11,798,576. The core novelty of the '576 patent lies in its method of using a predefined SNR range at a listener's location to dynamically and smoothly adjust gain, a specific process not explicitly detailed in these prior art documents.