Adaptive Stereo Width Control for Distortion-Free Widening
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Solution Overview
Problem
Conventional methods for stereo widening in audio devices often interfere with the original sound signal, causing detrimental side effects by applying fixed or constant widening factors that do not account for the characteristics of the input audio material, leading to unwanted sound distortions and alterations.
Innovation Solution
An adaptive stereo widening method that analyzes the input signal using Principal Component Analysis (PCA) and cross-correlation to determine a dynamic widening gain coefficient, applying signal processing 'out-of-band' to minimize interference with the original audio, adjusting the widening based on the input signal's characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If fixed or constant widening factors are applied to achieve stereo widening, then the stereo width is increased, but the original sound quality deteriorates due to unwanted distortions and alterations
Solution Approach 1:
The patent applies dynamic stereo widening by continuously analyzing the input signal characteristics (ambience level, center channel level, stereo separation) and adjusting the widening factor in real-time. This replaces fixed widening factors with adaptive control, allowing the system to increase stereo width when appropriate while maintaining original sound quality when the signal already contains sufficient ambience or center content.
Solution Approach 2:
The system changes multiple parameters simultaneously based on signal analysis: the widening factor is adjusted according to the measured ambience level, center channel level, and stereo separation. This multi-parameter adaptation allows optimal stereo widening while preventing distortions by responding to the actual characteristics of each audio segment.
2Device complexity
If fixed widening factors are used to simplify the processing, then the device complexity is reduced, but the adaptability to different audio materials deteriorates
Solution Approach 1:
The system performs self-analysis of the input signal to automatically determine the appropriate widening factor. By continuously measuring ambience level, center channel level, and stereo separation, the system serves itself with the information needed to adapt, eliminating the need for manual configuration or complex pre-programming for different audio materials.
Solution Approach 2:
The patent implements a feedback loop where the output of signal analysis (ambience level, center channel level, stereo separation measurements) feeds back to control the widening factor. This closed-loop control enables automatic adaptation to different audio materials while keeping the processing structure relatively simple and modular.
3Volume of moving object
If aggressive widening is applied to dry and narrow audio materials, then the stereo width is enhanced, but side effects such as overly space feeling and dampening of frequencies occur
Solution Approach 1:
The system dynamically adjusts the widening factor based on real-time analysis of the audio signal characteristics. For dry and narrow materials, the analysis detects low ambience levels and increases widening appropriately. For materials that already contain ambience or reverberation, the analysis detects high ambience levels and reduces widening, preventing overly space feeling and frequency dampening side effects.
Data Source
AI summary
A method of improving the listening experience when listening to music is provided. The object is to interfere as little as possible with the original music recording i.e. the input signal to the audio unit reproducing the music, but nevertheless provide a more full and wide stereo experience and thereby improved listening experience, particularly for replay installations where the loudspeakers are arranged in relatively close proximity to each other. The amount of stereo widening may sometimes be desired less than at other times. This is typically when the audio recording is already panned wide or produced including a certain amount of ambience and reverberation. At other times the level of widening can be increased giving a more exciting and “out-of-the-box” listening experience without side effects. An audio device is also provided.