Audio Gain Recovery with Noise Masking for Stable Quiet Recording
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Solution Overview
Problem
In quiet environments, such as concert halls, video cameras experience frequent fluctuations in audio levels due to clapping sounds, leading to noticeable noise fluctuations that cause a strange listening experience, as existing gain control mechanisms quickly adjust to prevent audio level exceedance and recover from sudden drops.
Innovation Solution
An audio processing apparatus with a detection unit, level control unit, gain control unit, noise generation unit, and combination unit that employs two recovery modes for gain adjustment and noise integration, ensuring consistent noise levels during rapid audio level changes, thereby minimizing perceived noise fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the gain control unit quickly increases the gain in the recovery operation to reduce audio fluctuations, then the response speed is improved, but the noise level fluctuations become more noticeable
Solution Approach 1:
The patent introduces noise as an intermediary element to mask the harmful noise fluctuations. By adding generated noise to the audio signal during recovery operations, the system creates a masking effect that makes the actual noise fluctuations imperceptible to listeners, thus resolving the contradiction between fast response and noise visibility
Solution Approach 2:
The patent converts the harmful effect of noise fluctuations into a benefit by using the same noise to mask the fluctuations. The noise that would normally be considered unwanted is instead utilized as a masking agent, transforming the harmful noise visibility into a beneficial concealment of gain recovery artifacts
2Stability of the object's composition
If the limit operation and recovery operation are repeated at short intervals to maintain audio level control, then the audio level stability is improved, but the noise fluctuations become more perceptible
Solution Approach 1:
The patent maintains continuous noise generation during recovery operations to continuously mask noise fluctuations. This continuous action ensures that regardless of how frequently limit and recovery operations repeat, the masking effect persists, preventing perceptible noise fluctuations while maintaining audio level stability
Solution Approach 2:
The generated noise serves as a mediator between the audio signal and the listener's perception. During repeated limit and recovery operations, this intermediary noise layer conceals the underlying noise fluctuations, allowing frequent gain adjustments without perceptible artifacts
Data Source
AI summary
A level detection unit detects a level of an audio signal. A level control unit controls the level of the audio signal according to a gain. A gain control unit performs a limit operation and a recovery operation according to the level of the audio signal. A noise generation unit outputs a noise signal. A combination unit combines the audio signal from the level control unit with the noise signal. In a second recovery mode, the gain control unit increases the gain in a longer time than in a first recovery mode. The gain control unit controls the noise generation unit to output a noise signal with a predetermined level in the first recovery mode, and to output a noise signal with a level according to the gain of the level control unit in the second recovery mode.