Audio Noise Reduction Circuit for Mobile Voice Calls

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Solution Overview

Problem

Mobile devices face challenges in reducing background noise during voice calls due to limited processing power and memory, making complex noise reduction methods unsuitable for implementation.

Innovation Solution

An audio processing device with two microphones that determines a noise reduction gain and attenuates signals using a noise reduction circuit, incorporating voice activity detection and single channel noise estimators to effectively reduce noise while maintaining speech quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If complex noise reduction methods such as source separation and acoustic scene analysis are used, then noise reduction performance is improved, but device complexity and processing power requirements increase making them unsuitable for mobile devices

Engineering Contradiction:

Improvenoise reduction performanceVSAvoidprocessing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and focuses only on the essential noise reduction functionality needed for mobile devices, eliminating complex components like full acoustic scene analysis while retaining effective noise suppression through simplified spectral subtraction and adaptive filtering methods

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs computationally lightweight algorithms that can be executed quickly with minimal processing resources, effectively replacing complex long-running noise reduction systems with simpler, faster-executing methods that achieve sufficient noise reduction performance for mobile applications

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If background noise reduction is applied during voice calls, then call quality is improved, but speech intelligibility may be compromised due to aggressive filtering

Engineering Contradiction:

Improvecall qualityVSAvoidspeech intelligibility

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent applies different processing strengths to different frequency bands and time segments of the audio signal, using voice activity detection to identify speech portions and applying gentler filtering to preserve speech intelligibility while maintaining aggressive noise reduction in non-speech portions

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent incorporates feedback mechanisms where the processed output is monitored and used to adjust filtering parameters in real-time, ensuring that speech intelligibility is maintained by detecting and preserving speech characteristics while removing background noise

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS10181329B2Audio processing circuit and method for reducing noise in an audio signal

Publication Date: 2019.01.15 INTEL CORP

AI summary

An audio processing device includes a first microphone configured to receive a first signal a second microphone configured to receive a second signal, a noise reduction gain determination circuit configured to determine a noise reduction gain based on the first signal and the second signal, a noise reduction circuit configured to attenuate the first signal based on the determined noise reduction gain, and an output circuit configured to output the attenuated signal.