Sound Field Control Apparatus Using Mode Decomposition for Acoustic Uniformity
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Solution Overview
Problem
Conventional sound field control technologies fail to accurately control acoustic space modes in real-world car environments due to non-ideal conditions, leading to suboptimal sound pressure distribution and performance.
Innovation Solution
A sound field control apparatus and method that uses multiple speakers and microphones to perform mode decomposition on sound pressure distributions, with a mode decomposition filter created based on actual sound pressure characteristics, employing sinusoidal and cosine functions to simulate and correct mode space frequencies for a flat sound pressure distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sound field control technologies are used in real-world car environments, then the system can operate with basic adaptive equalization, but the control accuracy of acoustic space modes deteriorates due to non-ideal conditions
Solution Approach 1:
The patent transforms the sound pressure distribution measurement into modal amplitude distribution through mode decomposition. By changing the parameter representation from spatial sound pressure to modal amplitudes, the system can accurately control acoustic space modes even in non-ideal car environments with reflections and standing waves.
Solution Approach 2:
The patent introduces mode decomposition filter as an intermediary that converts complex sound pressure distribution measurements into simplified modal amplitude information. This intermediary processing step enables accurate mode control by filtering out non-essential spatial variations and focusing on the fundamental acoustic modes.
2Measurement precision
If mode decomposition is performed using conventional methods, then the process can be implemented with standard filters, but the precision of mode amplitude control deteriorates in non-ideal acoustic conditions
Solution Approach 1:
The patent creates mode decomposition filters adaptively based on measured sound pressure distribution characteristics. Rather than using fixed conventional filters, the system dynamically adjusts filter parameters to match the actual acoustic environment, enabling precise mode amplitude measurement even when acoustic conditions deviate from ideal scenarios.
3Reliability
If adaptive equalization is used to correct acoustic transfer functions, then the system can produce a predetermined sound field at a control point, but the sound pressure distribution uniformity across the entire acoustic space deteriorates
Solution Approach 1:
The patent segments the sound field control into independent modal components through mode decomposition. By controlling each acoustic mode's amplitude separately rather than treating the sound field as a whole, the system achieves uniform sound pressure distribution across the entire acoustic space while maintaining accurate sound field reproduction at control points.
Data Source
AI summary
In a sound field control apparatus including multiple speakers, multiple microphones gathering sound radiated from the multiple speakers, a mode decomposition filter that performs mode decomposition on a sound pressure distribution, and a control filter that controls the input signals to be input to the multiple speakers such that the mode amplitudes of the modes decomposed by the mode decomposition filter can have a predetermined value, a sound pressure distribution in the acoustic space is measured, and the sound pressure distribution in the acoustic space is expressed by using a sinusoidal function and cosine function of a space frequency of the mode to be controlled in amplitude. The mode space frequency is corrected such that the expressed sound pressure distribution can be equal to the measured sound pressure distribution, and the filter coefficient for the mode decomposition filter is determined based on the mode space frequency obtained by the correction (corrected mode space frequency).