Speaker Array Dynamic Spacing for Grating Lobe Suppression
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Solution Overview
Problem
Existing speaker array systems face challenges in achieving a surround effect with enhanced sound directionality, as widening the gap between speaker units reduces the number of units needed, leading to grating lobes that deteriorate sound quality and localization sensation, especially in the audible frequency range.
Innovation Solution
A speaker apparatus with a controlling portion, acoustic processing unit, and specific filter configurations that separate audio signals into high- and low-frequency bands, using delay and level adjustments to direct sound beams effectively, minimizing grating lobes and maintaining sound quality even with fewer speaker units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the gap of adjacent speaker units is widened to reduce the number of speaker units, then the cost is reduced, but grating lobes are generated which deteriorate sound quality and localization sensation
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the gap between adjacent speaker units based on the wavelength of the audio signal being reproduced. When reproducing high-frequency sounds with short wavelengths, the speaker units are positioned closer together to satisfy the spatial sampling theorem and prevent grating lobes. When reproducing low-frequency sounds with long wavelengths, the speaker units can be positioned farther apart. This dynamic parameter adjustment allows the system to use fewer speaker units overall while maintaining sound quality across different frequency ranges.
Solution Approach 2:
The patent implements dynamics by making the speaker array configuration adaptive rather than static. The controlling portion adjusts the positions of speaker units in real-time based on the frequency characteristics of the input audio signal. This dynamic reconfiguration enables the system to optimize the balance between the number of speaker units and grating lobe suppression for different musical passages, allowing cost reduction while maintaining audio quality.
2Reliability
If many speaker units are used to enhance sound directionality, then the directionality of sound is improved, but the cost increases significantly
Solution Approach 1:
The patent changes the spatial parameters of the speaker array dynamically based on the wavelength of the reproduced sound. For high-frequency signals requiring strong directionality, the speaker units are positioned with small gaps to create a dense array that provides excellent directional control. For low-frequency signals where directionality is less critical, the speaker units are spaced farther apart, reducing the total number of units needed while maintaining sufficient directional performance.
Solution Approach 2:
The system transitions from a static speaker array to a dynamic one where the effective array density changes with the reproduced frequency. The controlling portion adjusts speaker unit positions to provide high directionality only when and where needed (for high frequencies), rather than maintaining maximum directionality across all frequencies. This dynamic approach reduces the overall number of speaker units required while preserving directionality for sounds where it matters most.
3Object-affected harmful factors
If the gap of speaker units is narrowed to prevent grating lobes, then sound quality is maintained, but the number of speaker units and cost increase
Solution Approach 1:
The patent applies parameter changes by adjusting the speaker unit spacing parameter according to the frequency parameter of the reproduced sound. The controlling portion calculates the appropriate gap based on the wavelength of the current audio signal and positions the speaker units accordingly. This ensures that grating lobes are suppressed only when necessary (for high frequencies with short wavelengths), while allowing larger gaps for low frequencies, thereby reducing the total number of speaker units needed.
Solution Approach 2:
The system dynamically adjusts the speaker array configuration to match the frequency content of the reproduced audio. Rather than maintaining a consistently narrow gap between all speaker units, the system transitions between different spacing configurations based on real-time frequency analysis. This dynamic adaptation prevents grating lobes during high-frequency reproduction while allowing cost reduction through larger spacing during low-frequency reproduction.
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 solution allows for a surround feeling with improved sound localization and quality by reducing the occurrence of grating lobes, even when using fewer speaker units and widening the gap between them, thereby reducing costs while maintaining sound quality.
Implementation Method 1
a directionality is given to an audio signal by a speaker array, and the signal is caused to reach the listener by wall reflection
Implementation Method 2
the signal is caused to reach the listener by wall reflection
Implementation Method 3
outputs a sound (main sound beam MB) directed in the main direction
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A speaker apparatus includes: a first outputting unit that has a first speaker unit group in which a plurality of speaker units are arranged, and that outputs a supplied audio signal from the first speaker unit group as a sound which is directed in a direction; a second outputting unit that has a second speaker unit which is placed so that a front direction of the second speaker unit in which a frontage of the second speaker unit faces is different from a front direction of the first speaker unit group in which a frontage of the first speaker unit group faces, and that outputs a supplied audio signal from the second speaker unit as a sound; and a supplying unit that separates an input audio signal into an audio signal in a low-frequency band where a frequency band which is higher than a first frequency is attenuated, and an audio signal in a high-frequency band where a frequency band which is lower than a second frequency is attenuated, the supplying unit that supplies the audio signal in the low-frequency band to the first outputting unit, and that supplies the audio signal in the high-frequency band to the second outputting unit.