MIMO Sound Wave Field Generation with Room Reflection Compensation
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Solution Overview
Problem
Current spatial sound field reproduction techniques, such as wave field synthesis and Ambisonics, face limitations in achieving high-quality spatial sound reproduction due to the need for a large number of loudspeakers and the inability to effectively handle room reflections, which are impractical in many environments like cars.
Innovation Solution
A multiple-input multiple-output (MIMO) system using a MELMS algorithm that equalizes sound wave fields by adjusting filter parameters to minimize pre-ringing and crosstalk, employing psychoacoustic constraints and adaptive filtering to optimize sound zone generation in vehicles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wave field synthesis or Ambisonics techniques are used to achieve high-quality spatial sound reproduction, then spatial accuracy and listening area are improved, but the number of loudspeakers required increases significantly
Solution Approach 1:
The patent extracts and compensates for the harmful effect of room reflections separately from the direct sound path. By identifying and processing reflected sound components independently, the system achieves accurate spatial reproduction without requiring the large number of loudspeakers typically needed for full wave field synthesis.
Solution Approach 2:
The patent introduces an intermediary processing stage that models and compensates for room acoustic effects. This intermediary layer between the loudspeakers and listeners allows the system to achieve accurate spatial reproduction with fewer loudspeakers by mathematically correcting for acoustic distortions.
2Measurement precision
If traditional sound field reproduction techniques are used, then spatial reproduction is achieved, but room reflections cause distortion of the reproduced wave field
Solution Approach 1:
The patent converts the harmful effect of room reflections into a measurable and compensatable parameter. By modeling the reflection paths and using this information to pre-compensate the loudspeaker signals, the system transforms the distortion-causing reflections into a known factor that can be corrected, thereby improving overall reproduction accuracy.
Solution Approach 2:
The patent applies preliminary anti-action by pre-compensating the loudspeaker signals for the expected distortion caused by room reflections. Before the sound reaches the listeners, the system calculates and applies corrective filters that counteract the anticipated reflective distortions, ensuring accurate wave field reproduction despite the presence of reflections.
3Measurement precision
If acoustic treatment is applied to achieve free-field conditions, then reflection distortion is reduced, but cost and practicality decrease significantly
Solution Approach 1:
The patent replaces the mechanical/acoustic approach of physical acoustic treatment with an electronic/digital signal processing approach. Instead of modifying the physical room environment with absorptive materials and acoustic panels, the system uses digital filters and signal processing to achieve the same effect of eliminating reflection distortion, thereby maintaining ease of implementation in environments like vehicles.
Data Source
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AI summary
A system and method are configured to generate a sound wave field around a listening position in a target loudspeaker-room-microphone system in which a loudspeaker array of K ≥ 1 groups of loudspeakers, with each group of loudspeakers having at least one loudspeaker, is disposed around the listening position, and a microphone array of M ≥ 1 groups of microphones, with each group of microphones having at least one microphone, is disposed at the listening position. The system and method include equalizing filtering with controllable transfer functions in signal paths upstream of the K groups of loudspeakers and downstream of an input signal path, and controlling with equalization control signals of the controllable transfer functions for equalizing filtering according to an adaptive control algorithm based on error signals from the K groups of microphones and an input signal on the input signal path. The system and method further include modeling of primary paths present in a desired source loudspeaker-room-microphone system in signal paths upstream of the groups of microphones and downstream of the input path.