Loudspeaker Device with Controlled Sound Fields
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Solution Overview
Problem
Conventional stereophonic loudspeaker systems suffer from unstable sound images when listeners move laterally, as the perceived position of sound elements changes due to varying distances from the loudspeakers, and their directional characteristics are frequency-dependent, leading to deteriorated sound reproduction for off-axis listeners.
Innovation Solution
A multi-loudspeaker configuration with adjustable beam direction and width, utilizing a combination of low-frequency omnidirectional and high-frequency directional loudspeakers, along with a bass-reflex system and digital signal processing units to control sound radiation patterns, ensuring stable stereophonic sound images and reduced frequency-dependent directivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional stereophonic loudspeaker systems are used with fixed directional characteristics, then the system structure is simple, but the sound image becomes unstable when listeners move laterally
Solution Approach 1:
The patent implements electronically controllable beamforming with adjustable beam directions and widths that can dynamically adapt to listener position and usage scenarios. Multiple loudspeaker units with independent control enable the system to transition between different radiation patterns, maintaining stable sound images while accommodating lateral listener movement through real-time parameter adjustment.
2Manufacturing precision
If loudspeaker units have narrow directional characteristics at high frequencies, then on-axis sound reproduction is improved, but off-axis sound reproduction deteriorates
Solution Approach 1:
The system uses electronically controlled beamforming to dynamically adjust beam width and direction based on listening position and content requirements. This enables the loudspeaker to maintain narrow beams for on-axis precision when needed while expanding beams for off-axis coverage when listeners are positioned away from the center, resolving the contradiction between on-axis quality and off-axis adaptability.
Solution Approach 2:
The patent employs digital signal processing to independently control the amplitude and phase of each loudspeaker unit, enabling continuous adjustment of beam direction and width parameters. This parameter control allows the system to optimize radiation patterns for different frequency ranges and listening positions, improving both on-axis precision and off-axis coverage.
3Ease of operation
If identical signals are provided to both loudspeakers, then the system operation is simple, but the perceived sound image position changes with listener lateral movement
Solution Approach 1:
The system incorporates automatic listener position detection and adaptive beamforming that self-adjusts to maintain stable sound images. The electronic control system automatically calculates and applies appropriate beam directions and widths based on detected or assumed listener positions, eliminating the need for manual signal adjustment while maintaining sound image stability.
Solution Approach 2:
The patent uses digital signal processing to dynamically adjust phase and amplitude parameters of each loudspeaker unit based on listener position. This enables the system to maintain stable sound images at different lateral positions by changing radiation parameters in real-time, while keeping the user interface simple and automatic.
4Reliability
If the loudspeaker system uses frequency-dependent directional characteristics, then the natural sound radiation pattern is maintained, but the directivity pattern changes significantly with frequency
Solution Approach 1:
The system employs independent phase and amplitude control of each loudspeaker unit across different frequency ranges, enabling electronic shaping of beam patterns that can compensate for natural frequency-dependent directivity. This allows the system to maintain consistent directional characteristics across frequencies when needed, while preserving natural radiation patterns when appropriate.
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 maintains a stable stereophonic sound image across different listening positions and optimizes sound reproduction by adapting beam direction and width, providing improved listening conditions in various use scenarios, including sound bars and car cabins, with reduced frequency-dependent directivity.
Implementation Method 1
The inner house portion (3) forms a bass-reflex system with the gap (6) wherein the inner house portion (3) forms a Helmholtz resonator with the gap (6)
Data Source
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AI summary
The invention relates to a loudspeaker system or device configured such that the sound field generated by the system or device is controllable. The system or device comprises Left (16, 18; 41, 43) and Right (15, 17; 42, 46) loudspeaker arrangements configured for radiating at least mid and high frequency sounds to the surroundings (R) and for controlling the sound radiation pattern (21, 22, 23, 24, 25, 26) of the left and right loudspeaker arrangements, respectively, such that the beam width and/or direction of the main lobe of the directivity pattern for the respective Left and Right loudspeaker arrangements can be varied; and at least one signal processor configured to process the signals to be provided to the loudspeakers of the respective loudspeaker arrangements such that the directional characteristics of the loudspeakers in each respective arrangement can be varied. The system or device may further comprise a low frequency arrangement comprising an arrangement of one or more loudspeakers (1 1, 12, 13, 14, 37) mounted in an enclosure (1 ) and configured such that the loudspeakers radiates sound energy to the surroundings (R). The low frequency arrangement may be configured as a bass-reflex enclosure with a wide port region. By means of the system or device according to the invention, the resulting directional characteristic of the system or device can be adapted to numerous specific use situations, for instance to obtain a stereo- stabilizing effect on a perceived sound image.