Loudspeaker Waveguide Interference Suppression
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Solution Overview
Problem
Loudspeaker systems face interference issues between mid-frequency drivers due to their spacing, leading to acoustic discontinuities and reduced performance, especially in line arrays where the distance between drivers results in destructive interference within specific frequency ranges.
Innovation Solution
The implementation of a loudspeaker system with mid-frequency drivers positioned on opposing sides of a high-frequency source connected to a waveguide, utilizing crossover circuitry to split the input signal into overlapping frequency ranges, ensuring the high-frequency source produces sound within the interference frequency range, thereby reducing destructive interference and enhancing sound homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mid-frequency drivers are spaced apart in a line array configuration, then the loudspeaker system can cover a wider frequency range and provide better bass response, but destructive interference occurs within specific frequency ranges leading to acoustic discontinuities
Solution Approach 1:
A waveguide is introduced as an intermediary component between the high-frequency compression driver and the mid-frequency drivers. The waveguide serves as a mediator that radiates sound energy into the intermediate frequency range, effectively bridging the gap between the high-frequency and mid-frequency drivers and suppressing destructive interference patterns
Solution Approach 2:
The system changes the operational parameters by having the high-frequency compression driver operate at reduced power levels within the intermediate frequency range (typically 200-1000 Hz) when driving mid-bass frequencies. This parameter adjustment allows the waveguide to effectively fill in the frequency gap without causing interference
2Reliability
If mid-frequency drivers are placed close together, then destructive interference is reduced, but the physical size of the loudspeaker enclosure decreases which limits bass response capability
Solution Approach 1:
The waveguide acts as a mediator that allows the high-frequency driver to contribute to mid-bass frequencies, effectively replacing the need for closely spaced mid-frequency drivers and enabling a more compact enclosure design while maintaining acoustic continuity
3Power
If the high-frequency compression driver operates at full power across all frequencies, then maximum sound pressure level is achieved, but acoustic interference and distortion increase in the intermediate frequency range
Solution Approach 1:
The system dynamically changes the operational parameters of the high-frequency compression driver by reducing its power output in the intermediate frequency range (200-1000 Hz) and relying on the waveguide to radiate these frequencies. This parameter adjustment eliminates interference and distortion while maintaining maximum overall sound pressure level through the combined output of all drivers
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 configuration effectively suppresses destructive interference and improves acoustic performance by operating the high-frequency source within the mid-frequency range, creating a more homogeneous sound field and extending the operational frequency range of the mid-frequency drivers.
Implementation Method 1
a waveguide configured to radiate the sound energy from said linear acoustic source, said waveguide having a proximal aperture for receiving sound energy and a distal aperture for radiating sound energy and a surface therebetween for controlling horizontal dispersion of the sound energy emitted therefrom
Implementation Method 2
signal processing circuitry comprising crossover circuitry that is configured to split an input signal into a first signal within a first frequency range and a second signal within a second frequency range, wherein the second frequency range overlaps with the first frequency range over an intermediate frequency range
Implementation Method 3
a frequency given by 344 m/s divided by 2d, beyond which destructive interference would otherwise occur between said first driver and said second driver in the absence of sound energy emitted by the waveguide
Data Source
Figure 1A~1B
Figure 1C
Figure 2
AI summary
Loudspeaker systems and assemblies are provided in which mid-frequency producing drivers (20, 20') are provided on opposing sides of a high frequency source comprising a linear high-frequency source (10) connected to a waveguide (40). Crossover circuitry is provided such that the acoustic output from the mid-frequency drivers (20, 20') overlaps with that of the high-frequency source (10) over an intermediate frequency range associated with acoustic interference between the mid-frequency producing drivers (20, 20'). In some embodiments, the mid-frequency producing drivers (20, 20') are recessed behind the output of the waveguide (40), and optionally angled outwardly from the waveguide (40), in order decrease the distance therebetween.