Loudspeaker Line Array Beam Steering for Stable Sound Imaging
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Solution Overview
Problem
Conventional loudspeaker systems face challenges in achieving accurate sound timbre, stable sound images, and flexible directional control over a wide listening area while minimizing visual impact, due to interactions with the listening environment and limitations in speaker design and placement.
Innovation Solution
A sound reproduction system featuring a column or array of drive units with integrated sound processing, allowing for improved steerability, directional control, and beam overlay, where drive units are arranged in a curved or staggered pattern with a narrow gap for sound output, and additional high-frequency drivers are used to enhance frequency range, with signal processing to adjust directionality and beam characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional stereo playback with two speakers is used, then an illusion of continuous sound stage can be created when listener is seated symmetrically, but the phantom image flops to nearest speaker when listener moves away from symmetry position, destroying stereo illusion
Solution Approach 1:
The sound reproduction system is divided into multiple independent drive units arranged in a vertical column array. Each drive unit can be independently controlled to generate sound waves, allowing the system to create stable phantom images across multiple positions rather than relying on a simple two-speaker stereo pair. This segmentation enables the sound stage to maintain accuracy regardless of listener position.
2Ease of operation
If horn-loaded speakers are used to achieve directional control, then controlled directional response is obtained, but distortion occurs at high levels due to non-linearity of air at horn mouth
Solution Approach 1:
The system replaces traditional horn-loaded mechanical directional control with an electronically controlled array of drive units. By using signal processing and phase control across multiple drive units, the system achieves directional control without the mechanical constraints and non-linearities of horn structures, thereby eliminating high-level distortion while maintaining directional precision.
3Ease of operation
If column speaker with long line of closely spaced identical speaker drive units is used, then degree of directionality in vertical plane is provided, but inability to maintain constant directivity over wide frequency range requires multiple horn speakers covering different frequency parts
Solution Approach 1:
The system employs dynamic signal processing to adjust the phase and amplitude of each drive unit based on frequency content. This allows a single column array to maintain constant directivity across the entire frequency range by electronically adapting the radiation pattern, eliminating the need for multiple fixed-frequency horn speakers and reducing overall system complexity.
4Object-affected harmful factors
If careful placement of speakers is used to reduce reflection problems, then some problems are reduced, but satisfying listening experience is provided only within limited area or sweet spot
Solution Approach 1:
The system changes the parameters of sound wave generation by controlling phase, amplitude, and timing of each drive unit in the column array. This enables the system to create multiple stable phantom images at different positions and to steer the sound beam dynamically, providing a satisfying listening experience across a wide area rather than局限于 a single sweet spot, while simultaneously managing reflection interference through controlled directivity.
Data Source
AI summary
A sound reproduction system includes one or more arrays of drive units, coupled with sound processing allowing improved steerability, directional control, width control, and/or beam overlay. A speaker column may comprise two arrays facing one another, the drive units being perpendicular to the speaker unit front, with the acoustic output of each line array being compressed, turned and output from an elongate slot. The drive units may be staggered with respect to those in the opposing array. The arrays may be arc-shaped else straight. Selective delays to simulate an arced pattern. Differential delays applied to the drive units in a sub-array allow beam steering. Additional drive units, such as high frequency drivers, may be added along the length of the elongate slot or elsewhere to increase the dynamic frequency range of the speaker system. A collocated sound processor and amplifier output stage may be integrated with the speaker unit.