Audio Signal Entropy Analysis for Sibilance Attenuation
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Solution Overview
Problem
Existing methods for reducing sibilance in audio signals, such as de-essers and physical windshields, often fail to accurately identify and attenuate sibilance, especially when the audio signal is rich in high-frequency harmonics, leading to potential removal of non-sibilant sounds.
Innovation Solution
A method and apparatus that calculate the entropy of an audio signal stream using discrete wavelet, Fourier, or frequency band transforms, comparing the calculated entropy to a threshold to switch a filter between active and inactive states, thereby accurately identifying and attenuating sibilance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high-frequency filtering is used to remove sibilance, then sibilance attenuation is improved, but non-sibilant high-frequency sounds are erroneously removed
Solution Approach 1:
The patent changes the detection parameter from simple frequency-based filtering to entropy-based analysis. By calculating entropy of audio signal portions and comparing against thresholds, the system can distinguish sibilance from other high-frequency content based on statistical properties rather than frequency alone, resolving the contradiction between sibilance attenuation and preservation of non-sibilant sounds
Solution Approach 2:
The patent introduces an intermediary detection mechanism (entropy calculator and comparator) between the audio signal and the filter. This intermediary analyzes the statistical properties of the signal and only activates filtering when sibilance is detected, preventing erroneous removal of non-sibilant high-frequency content while still achieving sibilance attenuation when needed
2Object-affected harmful factors
If physical windshields or pop guards are used to reduce sibilance, then sibilance attenuation is improved, but background noise and certain frequency ranges are adversely affected
Solution Approach 1:
The patent replaces the mechanical windshield/pop guard system with an electronic signal processing system. Instead of physically blocking sound waves before they reach the microphone, the system digitally analyzes and filters the captured signal, achieving sibilance attenuation without the side effects of physical barriers such as increased background noise or frequency attenuation
3Measurement precision
If entropy-based detection with wavelet transform is used, then sibilance identification accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent segments the audio signal into discrete portions and applies wavelet transform to each segment independently. This segmentation approach allows the computationally intensive entropy calculation to be performed on smaller data sets, reducing overall computational complexity while maintaining high detection accuracy through localized analysis of sibilant portions
Data Source
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AI summary
A method of processing an audio signal stream to attenuate an unwanted signal portion, the method comprising the steps of (a) providing a filter block having an input port and ah output port, the filter block having an inactive state in which signals pass from the input port to the output port without being filtered and an active state in which signals are filtered to attenuate an unwanted signal portion as they pass from the input port to the output port; (b) providing the audio signal stream to the input port of the filter; and, whilst the audio signal stream is being provided to the input port of the filter - (') calculating the entropy of at least a portion of the audio signal stream; hi) comparing the Calculated entropy to a threshold value; and, (iii) setting the state of the filter block to be either active or inactive depending on the comparison between the calculated entropy and the threshold value.