Pervasive Listening Gap Insertion for Playback Noise Estimation
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Solution Overview
Problem
Current noise compensation methods in audio playback systems face challenges in accurately estimating background noise levels due to the 'echo problem', where microphones capture both playback content and noise, leading to ineffective noise compensation, especially in low-cost devices with weak or non-existent echo cancellation capabilities.
Innovation Solution
The method involves inserting forced gaps into specific frequency bands of an audio playback signal to generate a modified signal, allowing a pervasive listener to monitor non-playback sound without significant perceptual artifacts, enabling improved noise estimation and compensation even without echo cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If forced gaps are inserted into frequency bands of audio playback signal, then noise estimation accuracy is improved, but perceptual artifacts may be introduced
Solution Approach 1:
The patent applies local quality by inserting gaps selectively in specific frequency bands rather than uniformly across all frequencies. The system identifies frequency bands where playback content has low energy or temporal redundancy, and inserts gaps only in those localized regions. This allows noise estimation to occur in frequency regions that are less perceptible to human listeners, thereby improving measurement precision while minimizing perceptual artifacts.
Solution Approach 2:
The patent implements partial action by not inserting gaps in all frequency bands simultaneously, but only in selected bands where it is least perceptible. The system performs noise estimation in a subset of frequency bands during playback, using partial gap insertion rather than complete silence periods. This approach provides sufficient information for accurate noise estimation while maintaining continuous audio playback in other frequency regions.
2Measurement precision
If gaps are inserted in playback signal to monitor non-playback sound, then background noise estimation is improved, but playback continuity is disrupted
Solution Approach 1:
The patent applies periodic action by inserting gaps at specific time intervals within frequency bands rather than creating continuous silence periods. The gaps are inserted periodically in a time-frequency grid pattern, allowing the system to sample noise characteristics at regular intervals while maintaining overall playback continuity. This periodic sampling provides sufficient data for noise estimation without prolonged interruptions to the audio experience.
Solution Approach 2:
The patent segments the audio signal into multiple frequency bands and time intervals, inserting gaps only in specific segments rather than throughout the entire signal. By dividing the playback signal into frequency bands and selectively inserting gaps in certain segments, the system maintains continuity in other segments. This segmentation allows noise monitoring to occur in discrete portions while the rest of the audio playback continues uninterrupted.
3Measurement precision
If echo cancellation is used to separate playback content from noise, then noise compensation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent extracts the noise estimation function from the traditional echo cancellation framework. Instead of relying on complex echo cancellation algorithms to separate playback content from noise, the system directly extracts noise information during gap periods when playback content is absent in specific frequency bands. This extraction approach bypasses the need for sophisticated echo cancellation processing, reducing device complexity while maintaining noise compensation accuracy.
Solution Approach 2:
The patent introduces forced gaps as an intermediary mechanism to facilitate noise estimation. These gaps serve as a mediator that creates temporary silence periods in specific frequency bands, allowing the microphone to capture pure noise signals without the confounding presence of playback content. This intermediary approach simplifies the noise separation problem compared to traditional echo cancellation methods, reducing computational complexity while improving measurement precision.
Data Source
AI summary
A pervasive listening method including steps of inserting at least one forced gap in a playback signal (thus generating a modified playback signal), and during playback of the modified playback signal, monitoring non-playback content (e.g., including by generating an estimate of background noise) in a playback environment using output of a microphone in the playback environment. Optionally, the method includes generation of the playback signal, including by processing of (e.g., performing noise compensation on) an input signal using a result (e.g., a background noise estimate) of the monitoring of non-playback content. Other aspects are systems configured to perform any embodiment of the pervasive listening method.