Multi-Band Compression with Dynamic Thresholds for Timbre Preservation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing audio playback devices suffer from distortion, particularly at increased playback levels, due to limited output capabilities, and multi-band compression methods often alter the timbre, resulting in an unnatural sound experience.
Innovation Solution
A multi-band compressor with time-varying thresholds computed using a timbre-preserving function that adjusts based on all frequency bands and fixed thresholds, allowing for gradual attenuation and minimizing distortion while maintaining natural sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-band compression is applied to reduce distortion, then distortion is reduced, but timbre is altered resulting in unnatural sound
Solution Approach 1:
The patent implements dynamic threshold adjustment where the compression threshold for each frequency band is not fixed but varies over time based on the signal characteristics. The threshold is computed dynamically using a timbre-preserving function that adapts to the input signal's spectral content, allowing the compressor to maintain natural timbre while effectively reducing distortion across different playback conditions
Solution Approach 2:
The system employs feedback mechanisms where the output of the timbre-preserving function feeds back into the threshold computation for each frequency band. This creates a closed-loop system that continuously monitors and adjusts compression parameters to preserve timbre characteristics while maintaining distortion reduction, ensuring that the compression adapts to maintain natural sound quality
Data Source
Figure 1A
Figure 1B~1C
Figure 2
AI summary
Distortion reducing multi-band compressor with timbre preservation is provided. Timbre preservation is achieved by determining a time-varying threshold in each of a plurality frequency bands as a function of a respective fixed threshold for the frequency band and, at least in part, an audio signal level and a fixed threshold outside such frequency band. If a particular frequency band receives significant gain reduction due to being above or approaching its fixed threshold, then a time-varying threshold of one or more other frequency bands are also decreased to receive some gain reduction. In a specific embodiment, time-varying thresholds can be computed from an average difference of the audio input signal in each frequency band and its respective fixed threshold.