Acoustic Transfer Function Evaluation Using Free-Field Subtraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems for evaluating acoustic transfer functions in complex environments are inefficient, particularly in reducing the load on electro-acoustic systems and requiring a large number of microphones for accurate characterization.
Innovation Solution
A system and method that utilize a deduction module to subtract the free-field part from an input signal, an estimation module to calculate an estimated corrective sound field based on a weighted series of plane wave functions, and a transfer function generation module to generate the acoustic transfer function, leveraging sparseness assumptions and iterative reweighted least square algorithms to reduce the number of microphones needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of microphones are used to accurately characterize the acoustic transfer function in complex environments, then measurement precision is improved, but device complexity and system load increase
Solution Approach 1:
The patent extracts and separates the free-field component from the total acoustic signal, allowing the system to focus measurement efforts only on the corrective sound field portion. This extraction enables accurate acoustic transfer function characterization with fewer microphones by eliminating the need to fully sample the entire sound field including the predictable free-field portion.
Solution Approach 2:
The patent transforms the measurement approach by changing from direct measurement of the complete acoustic transfer function to measuring only the corrective sound field component after removing the free-field part. This parameter change in the measurement strategy reduces the information that needs to be captured, thereby reducing the number of microphones required while maintaining accuracy.
2Measurement precision
If traditional methods are used to measure acoustic transfer function in complex environments, then comprehensive sound field coverage is achieved, but productivity and efficiency decrease due to system load
Solution Approach 1:
The patent performs preliminary subtraction of the free-field component before the main measurement and estimation process. By removing the predictable free-field portion in advance, the system reduces the complexity of subsequent measurements and calculations, thereby improving productivity and efficiency without sacrificing measurement precision.
Solution Approach 2:
The patent segments the acoustic transfer function measurement into distinct components: the free-field part and the corrective sound field part. This segmentation allows the system to handle each component separately, using efficient methods for the free-field portion and focused measurements for the corrective portion, thereby improving overall measurement efficiency.
3Reliability
If crosstalk cancellation is implemented to create enhanced spatial effects, then sound reproduction quality is improved, but system load increases significantly
Solution Approach 1:
The patent replaces complex full-bandwidth crosstalk cancellation processing with a more efficient approach that operates only on the corrective sound field component. By substituting the traditional heavy computational mechanism with a streamlined process that exploits the separated free-field/corrective field structure, the system maintains sound reproduction quality while reducing electro-acoustic system load.
Data Source
Figure 1~2
Figure 3~5
AI summary
A system (100) and a method for evaluating an acoustic transfer function, wherein the acoustic transfer function is a transfer function from one acoustic source to a reproduction area (RA) sampled by a limited number of microphone modules (120).