All-Pole Filter Sound Effect Generation
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Solution Overview
Problem
Existing sound effect generation methods, such as convolution using FIR filters or FFT, face challenges in achieving satisfactory quality while maintaining real-time properties and reducing computational complexity.
Innovation Solution
A sound effect generation method utilizing an all-pole filter with coefficients based on actual impulse response measurements, combined with a comb filter for attenuating specific band components, to generate reverberant sounds efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If convolution of impulse responses is performed using an FIR filter, then sound quality and naturalness are improved, but the amount of computation becomes huge
Solution Approach 1:
The patent transforms the FIR filter parameters into IIR filter parameters by fitting an all-pole model to the impulse response data. This parameter transformation changes the computational characteristics from O(N) to O(M) where M << N, while preserving the essential acoustic characteristics of the original impulse response.
Solution Approach 2:
The patent extracts only the most important characteristics of the impulse response by fitting an all-pole model, separating the essential reverberation properties from the complete impulse response data. This extraction allows reproduction of the acoustic environment with significantly reduced data and computation.
2Manufacturing precision
If convolution of impulse responses is performed using FFT, then sound quality is improved, but real-time properties deteriorate
Solution Approach 1:
The patent changes the computational approach from frequency domain convolution using FFT to time domain filtering using IIR filters. This parameter change enables real-time processing while maintaining acceptable sound quality by using the recursive structure of IIR filters that can process samples continuously with constant computational effort.
3Productivity
If a Schroeder scheme with all-pass filters is used, then real-time properties and computation amount are improved, but sound quality is degraded
Solution Approach 1:
The patent changes the filter structure from all-pass filters (Schroeder scheme) to all-pole filters fitted to actual impulse response measurements. This parameter change allows the system to maintain real-time processing capabilities while significantly improving sound quality by directly modeling the measured acoustic characteristics of the target environment.
Solution Approach 2:
The patent performs preliminary fitting of the all-pole model to the impulse response data offline, storing only the filter parameters. During real-time operation, only the parameter-based filtering is needed, combining offline analysis with efficient online processing to achieve both quality and speed.
Data Source
AI summary
This sound effect generation method includes: generating a sound effect with respect to a sound by using an all-pole filter having a coefficient generated on the basis of an actual measurement value of impulse response; and outputting the sound effect.