Sound System Beamforming and Direct Sound Suppression
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Solution Overview
Problem
Existing sound systems, including home cinema and soundbars, face limitations in reproducing surround sound effectively due to complexity and quality issues, particularly with low frequencies, where beamforming is inadequate, leading to direct sound reaching listeners instead of being reflected, resulting in poor spatial perception.
Innovation Solution
A calculation unit for a sound system that uses a combination of beamforming and direct sound suppression techniques, such as dipoling and sound cancelation, to improve surround sound reproduction by filtering audio signals and manipulating radiation patterns, ensuring sound is canceled or reduced in the listening direction, particularly for low frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If beamforming is used to project sound to side/rear, then spatial sound reproduction is improved, but low frequency sound cannot be effectively projected due to aperture limitations
Solution Approach 1:
The patent segments the audio signal into different frequency bands (low frequencies and medium/high frequencies) and processes each band separately using different techniques. Low frequencies are handled by front loudspeakers while medium/high frequencies use beamforming for directional projection to side and rear, resolving the contradiction between spatial accuracy and low frequency capability
Solution Approach 2:
Different parts of the frequency spectrum are assigned different reproduction qualities and methods. The patent applies beamforming specifically to medium and high frequency bands where aperture is sufficient, while using conventional loudspeaker reproduction for low frequencies, optimizing each frequency range according to its physical constraints
2Measurement precision
If surround speakers are installed for true surround sound, then spatial perception is improved, but device complexity and cabling requirements increase
Solution Approach 1:
The front loudspeaker array is designed to perform multiple functions: conventional sound reproduction for low frequencies and beamforming for medium/high frequencies. This multi-functionality allows the system to achieve surround sound effects without requiring separate surround speakers, reducing system complexity while maintaining spatial perception quality
Solution Approach 2:
The patent changes the operational parameters of the loudspeaker array by dynamically adjusting beamforming weights and signal processing parameters based on frequency content. This allows the same physical array to produce different radiation patterns (omnidirectional for low frequencies, directional for medium/high frequencies), achieving surround effects without additional hardware
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
Enhances surround sound reproduction quality without increasing complexity by effectively canceling or reducing direct sound in the listening direction, allowing for a more spacious and accurate spatial sound perception, even at low frequencies, using the same soundbar setup.
Implementation Method 1
Each of the transducers 20a to 20d is outputting a sound signal
Implementation Method 2
The listener 27 is situated in front of the array 20, but the sound signals are perceived by the listener 27 also from the sides, since they are reflected by the lateral walls 25
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A calculation unit for a sound system comprises input means, a processor and output means. The input means have the purpose to receive an audio stream to be reproduced using the sound system. The output means has the purpose to control the sound system based on a first and a second plurality of individual audio signals. The processor is configured to calculate the first plurality of audio signals such that beamforming is performed by the array and to calculate the second plurality of individual audio signals to perform, using the sound system, direct sound suppression such that sound is canceled towards a listening direction. Furthermore, the processor filters at least the second plurality using a second passband characteristic comprising a second portion of the entire frequency range.