Speaker Array Beam Pattern Adjustment for Listener Distance
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Solution Overview
Problem
Speaker arrays face challenges in maintaining a consistent direct-to-reverberant sound energy ratio as listeners move, as the direct sound energy increases while reverberant sound energy remains relatively unchanged, affecting sound quality.
Innovation Solution
A directivity adjustment device that includes a distance estimator, directivity compensator, and array processor, which detects the listener's distance and adjusts the beam pattern's directivity index to maintain a constant direct-to-reverberant sound energy ratio by processing audio signals to drive transducers in the speaker array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the listener moves closer to the speaker array, then the direct sound energy increases, but the direct-to-reverberant sound energy ratio becomes unbalanced
Solution Approach 1:
The beam pattern directivity is dynamically adjusted based on the detected distance between the listener and speaker array. The system continuously modifies the directivity index to maintain a constant direct-to-reverberant energy ratio, transitioning from static to adaptive beam forming that responds to listener position changes.
Solution Approach 2:
The system uses a distance estimator to detect listener position and feeds this information back to the array processor, which adjusts the beam pattern accordingly. This closed-loop feedback mechanism ensures the direct-to-reverberant ratio remains balanced regardless of listener distance.
2Use of energy by moving object
If a narrow beam pattern is used to increase direct sound energy, then the direct-to-reverberant ratio increases, but the coverage area decreases
Solution Approach 1:
The beam pattern width is dynamically controlled based on listener distance. When the listener is far away, a narrower beam concentrates energy to maintain adequate direct sound levels. When the listener is close, the beam widens to provide broader coverage while maintaining appropriate direct-to-reverberant balance.
Solution Approach 2:
The system changes the directivity index parameter of the beam pattern based on detected listener distance. This parameter adjustment allows the beam pattern to adapt its shape and coverage area, optimizing both direct sound energy delivery and spatial coverage according to listener position.
3Area of stationary object
If a wide beam pattern is used to increase coverage area, then the direct-to-reverberant ratio decreases, but the direct sound energy at the listener decreases
Solution Approach 1:
The system dynamically adjusts beam pattern width based on listener distance. At far distances, the beam narrows to concentrate energy and maintain adequate direct sound levels. At close distances, the beam widens to provide broader coverage while the increased direct sound energy from proximity maintains an appropriate direct-to-reverberant ratio.
Solution Approach 2:
The directivity index parameter is adjusted based on listener distance to optimize the trade-off between coverage area and direct sound energy. This parameter change allows the system to adapt the beam pattern shape, ensuring adequate energy delivery to distant listeners while providing broad coverage for close listeners.
Data Source
AI summary
A directivity adjustment device that maintains a constant direct-to-reverberant ratio based on the detected location of a listener in relation to the speaker array is described. The directivity adjustment device may include a distance estimator, a directivity compensator, and an array processor. The distance estimator detects the distance between the speaker array and the listener. Based on this detected distance, the directivity compensator calculates a directivity index form a beam produced by the speaker array that maintains a predefined direct-to-reverberant sound energy ratio. The array processor receives the calculated directivity index and processes each channel of a piece of sound program content to produce a set of audio signals that drive one or more of the transducers in the speaker array to generate a beam pattern with the calculated directivity index.