Loudspeaker Directivity Control via Phase-Altering Side Radiation
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Solution Overview
Problem
Loudspeaker systems with bass sound sources typically have low directivity due to the large wavelengths of lower frequencies, which limits their ability to provide uniform sound coverage and increases sound emission in undesirable directions, especially in the low frequency range.
Innovation Solution
The integration of a first chamber with a side sound exit opening and a directivity bass sound source within the loudspeaker enclosure, along with a treble and/or midrange sound source, allows for increased directivity by phase-altering lateral sound radiation, and the use of time-delayed audio signals in separate transmission paths to control sound pressure and cancellation in the main and reverse directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a loudspeaker box has standard enclosure dimensions, then the device complexity is reduced, but the directivity in the low frequency range deteriorates
Solution Approach 1:
The loudspeaker system is divided into multiple independent sound sources: a first bass sound source and a second bass sound source with different radiation characteristics. The second bass sound source is positioned at a distance from the first, creating separate acoustic paths that can be controlled independently through time-delayed signals, enabling directivity control without increasing enclosure dimensions.
Solution Approach 2:
The patent introduces a temporal dimension by applying time delays to the audio signals of the second bass sound source relative to the first. This time-based differentiation creates constructive and destructive interference patterns in space, achieving directivity control through the time domain rather than requiring larger spatial dimensions.
2Quantity of substance
If the wavelength of bass frequencies is large, then the physical laws of sound propagation are determined, but the directivity is reduced
Solution Approach 1:
The patent changes the phase parameter of the audio signal for the second bass sound source by applying a time delay. This phase modification creates frequency-dependent interference patterns that produce directional radiation characteristics, allowing directivity control that overcomes the omnidirectional tendency caused by long bass wavelengths.
3Ease of operation
If sound is radiated omnidirectionally, then the sound coverage is uniform in all directions, but the sound emission in undesirable directions increases
Solution Approach 1:
The patent converts the harmful omnidirectional radiation into a beneficial directional pattern by using the second bass sound source with time-delayed signaling. The sound that would naturally radiate in all directions is instead used to create constructive interference in desired directions and destructive interference in undesirable directions, transforming the omnidirectional characteristic into a controlled directional pattern.
4Ease of manufacture
If the radiation area is 90 degrees, then the directivity requirement is met, but the enclosure width must be 1 meter, increasing device complexity
Solution Approach 1:
The patent replaces the mechanical approach of achieving directivity through large physical dimensions (1-meter enclosure width) with an electronic/acoustic approach using time-delayed signal processing. By controlling the phase relationship between two bass sound sources, the system achieves the desired 90-degree radiation area without requiring proportionally large enclosure dimensions.
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 enhances the directivity of the loudspeaker system across the entire frequency range, providing more uniform sound coverage and reducing rear sound emission, thereby increasing the maximum gain before feedback onset.
Implementation Method 1
at least one first directivity bass sound source (R-LF1), arranged in the first chamber, having a main direction of radiation at the side in regard to the main direction of radiation
Implementation Method 2
The second bass sound source (LF1) is coupled to a second audio amplifier output signal, wherein the second audio amplifier output signal has a time delay relative to the first audio amplifier output signal
Implementation Method 3
increases the directivity of the loudspeaker system across the entire frequency range, providing more uniform sound coverage and reducing rear sound emission
Data Source
AI summary
A loudspeaker system includes a loudspeaker enclosure having a front and a rear. Further, the loudspeaker system includes at least one first bass sound source, arranged in the loudspeaker enclosure, having a main direction of radiation at the front and at least one treble and/or midrange sound source. At least one first chamber of the loudspeaker enclosure is provided with a first sound exit opening that is at the side in regard to the main direction of radiation. The loudspeaker system further comprises at least one first directivity bass sound source that is arranged in the first chamber.