Acoustic Waveguide Mode Control via Driver Positioning
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Solution Overview
Problem
Acoustic waveguide systems face challenges in achieving a flat frequency response due to excitation of undesirable modes, leading to peaks and dips in the frequency spectrum, which are undesirable acoustically.
Innovation Solution
The placement of acoustic drivers in the waveguide is optimized such that the total excitation of specific modes is minimized by positioning them at locations where the modal function values are equal in magnitude but opposite in sign, or by using specific formulas to determine their positions and gains, ensuring that the total excitation of certain modes is substantially zero.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If acoustic drivers are placed in the waveguide to increase acoustic output, then the frequency response develops peaks and dips due to mode excitation, but the uniformity of frequency response deteriorates
Solution Approach 1:
The patent applies local quality by positioning acoustic drivers at specific locations along the waveguide where the modal function has particular characteristics. Each driver is placed at a predetermined position calculated to excite only desired modes while avoiding undesirable modes, creating localized excitation patterns that collectively produce a uniform frequency response across the entire system.
Solution Approach 2:
The patent utilizes parameter changes by varying the positions of acoustic drivers along the waveguide according to calculated formulas involving modal functions. By changing the spatial parameters (positions) and operational parameters (gains) of the drivers, the system achieves mode control that eliminates peaks and dips in the frequency response while maintaining acoustic output.
2Reliability
If acoustic drivers are positioned to excite specific modes, then the excitation of undesirable modes increases, but the complexity of driver placement calculation increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating the optimal positions and gains for acoustic drivers using modal function analysis before actual system implementation. The formulas and methods provided allow designers to determine exact driver placements in advance, ensuring reliable mode control without requiring complex real-time calculations or iterative adjustments during system operation.
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
This approach effectively reduces the excitation of undesirable modes, resulting in a smoother frequency response with reduced peaks and dips, providing a more uniform acoustic output across a wider range of frequencies.
Implementation Method 1
the acoustic drivers radiate into the waveguide so that radiation from each, acoustic driver excites one mode at a position in the waveguide at which a modal function corresponding with the one mode is non-zero
Implementation Method 2
an acoustic waveguide characterized by modes
Data Source
AI summary
An acoustic device including a first acoustic waveguide having two open ends; a second acoustic waveguide; and an acoustic driver having a first and second radiating surface positioned so that the first: radiating surface radiates into the first waveguide and the second surface radiates into the second waveguide. An acoustic device including an acoustic driver and an acoustic waveguide with two open ends. A method for making the acoustic device.