Audio Signal Processing for Level-Based Quantization Noise Attenuation
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Solution Overview
Problem
Existing techniques for removing quantization noise often inadvertently remove audible sound components, degrading sound quality.
Innovation Solution
A signal processing device that acquires quantized sound data and determines a control amount for quantization noise based on the sound data's level, allowing for targeted attenuation of noise while preserving the original sound components, using a combination of frequency domain processing and attenuation based on sound level and frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If uniform removal of quantization noise is applied to all frequency components, then quantization noise is reduced, but originally existing 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, frequency components with lower levels (likely noise) receive greater attenuation, while frequency components with higher levels (likely sound signals) receive less attenuation. This localized differentiation resolves the contradiction by treating noise and sound components differently rather than uniformly.
Solution Approach 2:
The patent changes the attenuation parameter dynamically based on the level of each frequency component. By adjusting the attenuation amount according to the signal level, the system achieves selective noise reduction where lower-level components (noise) are attenuated more than higher-level components (sound), thus resolving the contradiction between noise removal and sound preservation.
2Object-affected harmful factors
If quantization noise attenuation is applied, then noise influence is reduced, but sound components may be degraded
Solution Approach 1:
The patent implements local quality by applying spatially-varying attenuation across the frequency spectrum. Each frequency component receives attenuation proportional to its noise-like characteristics, allowing noise reduction in specific frequency regions while preserving sound components in other regions, thus maintaining sound component integrity while reducing noise influence.
Solution Approach 2:
The patent replaces uniform mechanical attenuation with a sophisticated control system that uses level detection and conditional logic to determine attenuation amounts. This substitution of simple mechanical noise filtering with an intelligent, adaptive control mechanism allows the system to distinguish between noise and sound components, reducing noise while preserving sound integrity.
Data Source
AI summary
A converter includes a time window cut-out block, a fast Fourier transform (FFT) block, an attenuation amount limitation block, a quantization noise attenuation block, an overtone generation block, an inverse fast Fourier transform (IFFT) block, and a time window resynthesis block. The attenuation amount limitation block determines the maximum attenuation amount of quantization noise to be attenuated in the quantization noise attenuation block based on the magnitude of a signal level of sound data supplied from the time window cut-out block. The quantization noise attenuation block adjusts amplitude in a frequency domain based on the maximum attenuation amount determined by the attenuation amount limitation block, to attenuate the quantization noise.