Frequency-Domain Audio Processing for Selective Quantization Noise Attenuation
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Solution Overview
Problem
Existing techniques for removing quantization noise inadvertently remove original sound components along with the quantization noise, degrading sound quality.
Innovation Solution
A signal processing device that determines quantization noise control based on sound data level and frequency, attenuating noise selectively to preserve original sound components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If uniform removal of quantization noise is applied, then quantization noise is reduced, but original sound components are also removed together with the noise
Solution Approach 1:
The patent applies different attenuation amounts to different frequency components based on their individual characteristics. Specifically, it calculates an attenuation amount for each frequency component by comparing the signal level with the quantization noise level at that frequency, thereby selectively removing noise while preserving original sound components. This local differentiation resolves the contradiction between noise removal and sound quality preservation.
Solution Approach 2:
The patent changes the attenuation parameter dynamically based on the signal characteristics at each frequency. By calculating the attenuation amount as a function of signal level and noise level at each frequency component, the system adapts the noise removal strength to local conditions, achieving effective noise reduction without uniformly degrading sound quality.
2Manufacturing precision
If quantization noise is attenuated selectively based on sound data level and frequency, then original sound components are preserved, but processing complexity increases
Solution Approach 1:
The patent divides the frequency spectrum into discrete frequency components and processes each component independently. By segmenting the signal processing into frequency-domain components, the system can apply different attenuation strategies to different frequencies based on their noise characteristics, achieving selective noise removal without requiring complex time-domain processing.
Solution Approach 2:
The patent replaces complex time-domain noise removal mechanisms with frequency-domain processing using Fourier transform. This substitution simplifies the processing by transforming the problem into a more manageable frequency domain where noise and signal can be separated and processed independently, reducing overall processing complexity while maintaining effectiveness.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A converter 2 includes a time window cut-out block 21, a fast Fourier transform (FFT) block 22, an attenuation amount limitation block 23, a quantization noise attenuation block 24, an overtone generation block 25, an inverse fast Fourier transform (IFFT) block 26, and a time window resynthesis block 27. The attenuation amount limitation block 23 determines the maximum attenuation amount of quantization noise to be attenuated in the quantization noise attenuation block 24 based on the magnitude of a signal level of sound data supplied from the time window cut-out block 21. The quantization noise attenuation block 24 adjusts amplitude in a frequency domain based on the maximum attenuation amount determined by the attenuation amount limitation block 23, to attenuate the quantization noise.