Multi-band Dynamics Processor for Audio Intermodulation Distortion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Dynamics processors in electronic devices often cause unwanted intermodulation distortion (IM) across various frequency bands, leading to a decrease in audio output quality due to the generation of additional signal content at harmonic and non-linearly related frequencies, particularly in wideband applications.
Innovation Solution
A multi-band dynamics processor (MBDP) system is employed to split audio input signals into multiple frequency bands, apply adaptive gain adjustments based on dynamic changes, and use signal event detection and gain smoothing to minimize IM, ensuring each frequency band is processed independently to maintain quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a dynamics processor is used to process wideband audio signals, then audio processing capability is improved, but intermodulation distortion increases
Solution Approach 1:
The patent divides the wideband audio signal into multiple frequency bands using filter banks, processes each band separately through independent dynamics processors, and then recombines them. This segmentation prevents intermodulation distortion because each narrowband processor operates independently without generating IM products across different frequency bands, while still providing comprehensive audio processing coverage across the entire frequency spectrum.
2Productivity
If multiple frequency bands are processed together, then overall audio processing is improved, but intermodulation distortion increases
Solution Approach 1:
The audio signal is segmented into multiple frequency bands using filter banks, with each band processed by a separate dynamics processor. This allows simultaneous processing of multiple frequency bands while avoiding intermodulation distortion that would occur if all bands were processed together by a single wideband processor.
3Device complexity
If a single dynamics processor handles all frequency bands, then device complexity is reduced, but audio output quality deteriorates
Solution Approach 1:
The system uses multiple dynamics processors, each dedicated to a specific frequency band, rather than a single processor handling all bands. This segmentation improves audio output quality by preventing intermodulation distortion while maintaining manageable device complexity through modular architecture with standardized processing blocks.
Data Source
AI summary
Methods and devices for reducing intermodulation distortion are described herein. In response to receiving an audio input signal, N filtered audio signals may be generated by a filter bank, corresponding to N different frequency bands. The N filtered audio signals may be delayed by a delay time D, and a determination of whether an audio frame of the filtered audio signals includes an audio event or a non-audio event. A signal level estimation may then be determined, the signal level estimation indicating an expander, a compressor, or no compression effects being present. An amount of gain is determined and applied to the delayed audio signals, which are summed across the N frequency bands to generate a full-band audio signal. In some embodiments, the full-band audio signal may be applied to a limiter to reduce any audio clipping, and a final audio signal may be generated.