Speaker Array Directivity Peak Shift via Wall Reflection
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Solution Overview
Problem
Existing speaker systems face limitations in controlling directivity for signals across a wide frequency range, particularly in narrow spaces like automobiles, where the length of the speaker array restricts the lower frequency limit of the control band, leading to disturbances in the sound field and reduced audibility.
Innovation Solution
A speaker system with a linear array of speakers that undergoes filter processing and amplification, where the directivity peak is shifted toward a wall surface, allowing for control of directivity across a wider frequency band by utilizing reflection of sounds on the wall surface, and separate processing for bass and treble components to enhance audibility and prevent unwanted sound leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the speaker array length is increased to lower the lower frequency limit of the control band, then the directivity control range is improved, but the device size and space requirements increase
Solution Approach 1:
The patent utilizes the spatial dimension created by the wall surface to extend the effective speaker array length. By shifting the directivity peak toward the wall surface and leveraging sound reflections, the system achieves the acoustic performance of a longer array without physically extending the speaker array itself, thus resolving the contradiction between control range and physical dimensions.
Solution Approach 2:
The wall surface acts as an intermediary element that enables extended directivity control. The filter processing shifts the directivity peak toward the wall, and the wall's reflective properties effectively extend the speaker array's acoustic length, allowing lower frequency control without increasing the physical array length.
2Adaptability or versatility
If the speaker array length is increased to raise the upper frequency limit, then the control band width is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent changes the frequency response parameters through filter processing applied to each speaker element. By adjusting the filtering characteristics and shifting the directivity peak toward the wall surface, the system expands the control band width without adding more speakers or increasing array complexity, thus resolving the contradiction between control band width and device complexity.
3Adaptability or versatility
If filter processing is applied to shift the directivity peak toward the wall surface, then the lower frequency limit is lowered, but the sound field distribution becomes uneven
Solution Approach 1:
The patent converts what would normally be considered a harmful effect (uneven sound field distribution due to wall proximity) into a beneficial feature. By intentionally shifting the directivity peak toward the wall surface through filter processing, the system utilizes wall reflections to achieve lower frequency control, transforming the potential problem of uneven distribution into an advantage for expanding the control band.
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 system effectively lowers the lower frequency limit of the control band and raises the upper frequency limit, ensuring desired directivity and natural audibility for the intended user while minimizing sound exposure to others, even in confined spaces.
Implementation Method 1
A peak of the directivity of reproduced sounds, corresponding to the first signal, that have been output from the speaker array, the peak being in the array direction, is shifted toward the wall surface due to the first filter processing
Data Source
AI summary
A speaker system has a speaker array including a plurality of first speakers and a first filter array. A peak of the directivity of reproduced sounds output from the speaker array. And the peak being in a direction in which the plurality of first speakers are arranged, is shifted toward a wall surface due to first filter processing performed by the first filter array.