Loudspeaker Array SPL Mapping with Boundary-Element Wave Modeling
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Solution Overview
Problem
Current sound reinforcement system design methods, such as the Complex Directivity Point Source model, fail to account for wave physics aspects like reflection, diffraction, and shadowing/occlusion, limiting design freedom and introducing errors, especially for low-frequency loudspeakers, due to computational complexity and the need for impractical measurements.
Innovation Solution
A computer-implemented method using numerical simulations that include reflection, diffraction, and shadowing/occlusion, employing Lumped Element Models and Boundary Element Methods to generate a Sound Pressure Level (SPL) map, utilizing pre-stored acoustic velocity data and coarse meshing to reduce computational complexity, enabling real-time design assistance on modern hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Complex Directivity Point Source (CDPS) model is used to predict SPL, then phase interactions between sources are captured accurately, but wave physics aspects such as reflection, diffraction, and shadowing/occlusion are not considered
Solution Approach 1:
The patent segments the acoustic field calculation into two distinct parts: (1) near-field calculations using CDPS for phase interaction accuracy, and (2) far-field calculations using Boundary Element Method for wave physics accuracy. This segmentation allows each method to be applied where it is most effective, resolving the contradiction between phase interaction accuracy and wave physics accuracy.
Solution Approach 2:
The patent introduces an intermediary approach by using the Boundary Element Method to calculate surface pressures on loudspeaker cabinets, which then serve as boundary conditions for far-field SPL predictions. This intermediary calculation bridges the gap between near-field point source models and far-field wave physics, enabling both phase interaction accuracy and wave physics accuracy to coexist.
2Reliability
If full wave domain simulations with detailed meshing are used to include reflection, diffraction, and shadowing, then wave physics accuracy is improved, but computational cost and time increase excessively
Solution Approach 1:
The patent applies partial action by using coarse meshing that is sufficient for capturing low-frequency wave physics (20-200Hz) but not excessive for higher frequencies. This partial meshing approach provides adequate wave physics accuracy for the target frequency range while maintaining computational efficiency, avoiding the need for fine meshing that would be computationally prohibitive.
Solution Approach 2:
The patent changes the meshing parameter from fine to coarse, and changes the frequency range parameter to focus on low frequencies (20-200Hz). These parameter changes reduce the computational complexity and time required for wave domain simulations while maintaining adequate accuracy for bass loudspeaker design, thus resolving the contradiction between wave physics accuracy and computational speed.
3Reliability
If complex full-wave simulations are implemented, then wave physics effects are accurately modeled, but the device complexity and computational resources required increase significantly
Solution Approach 1:
The patent segments the computational model into distinct modules: CDPS for near-field phase interactions, Boundary Element Method for far-field wave physics, and hybrid integration. This segmentation reduces overall model complexity by allowing each module to be developed and validated independently, while maintaining high reliability through the complementary strengths of each approach.
Solution Approach 2:
The patent uses pre-measured directivity data from loudspeaker measurements as input for the CDPS model, copying real-world acoustic characteristics into the simulation. This copying approach maintains reliability by grounding the complex hybrid model in actual measured data, while reducing the need for complex first-principles modeling of every acoustic detail.
4Measurement precision
If direct measurements of bass loudspeakers are conducted to ensure CDPS accuracy, then measurement precision is improved, but practical difficulties and errors increase due to anechoic chamber size limitations
Solution Approach 1:
The patent substitutes mechanical measurement systems with numerical simulation systems. Instead of requiring physical anechoic chambers for bass loudspeaker measurements, the patent uses Boundary Element Method simulations to predict far-field behavior from coarse meshing and measured surface pressures. This substitution eliminates the mechanical constraint of anechoic chamber size while maintaining measurement precision through computational accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method provides accurate SPL maps in seconds, allowing for optimized loudspeaker array configurations that enhance sound uniformity and quality across venues, overcoming the limitations of existing methods by incorporating wave physics without excessive computational burden.
Implementation Method 1
The inventor has discovered that this assumption is wrong and that current computing hardware is capable of running full wave domain simulations on end user computing machines at low frequencies (20-200Hz), using a numerical method that does not require meshing of domains and requires only a relatively coarse meshing of boundaries, due to the long wavelengths involved.
Implementation Method 2
The CDPS method captures the phase interactions between sources quite accurately and, providing that the simulation fits within the constraints imposed by the measured directivity data, the results usefully approximate reality. However, there are some significant disadvantages to this approach, the principal one being that it does not consider all aspects of wave physics, such as reflection, diffraction, and shadowing/occlusion.
Implementation Method 3
The CDPS method captures the phase interactions between sources quite accurately and, providing that the simulation fits within the constraints imposed by the measured directivity data, the results usefully approximate reality. However, there are some significant disadvantages to this approach, the principal one being that it does not consider all aspects of wave physics, such as reflection, diffraction, and shadowing/occlusion.
Data Source
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AI summary
A method of generating a Sound Pressure Level, SPL, map for a venue. The method comprises receiving a loudspeaker system configuration including loudspeaker unit data. A data library is accessed to obtain a loudspeaker unit type data including a geometry of loudspeaker unit types and acoustic velocity information at surface locations of the loudspeaker unit types. A mesh representation of the loudspeaker system is obtained and used to generate system acoustic velocity information at surface locations of the mesh representation of the loudspeaker system. A numerical method is used to calculate surface pressures at surfaces of the mesh representation of the loudspeaker system, based on said system acoustic velocity information. A far field pressure at a multiplicity of observation points within said venue is then obtained and an SPL map generated based on the obtained far field pressures.