Low-Frequency Channel Scaling for Flexible Loudspeaker Arrays
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Solution Overview
Problem
Current multichannel audio systems, particularly wave-field synthesis systems, face challenges in generating low-frequency channels that reduce level artefacts and are cost-effective, as they require a large number of loudspeakers, leading to high costs and inefficiencies in sound reproduction across varying environments.
Innovation Solution
A method for generating a low-frequency channel using audio objects with calculated scaling values based on their descriptions, summing scaled object signals to create a composite signal, and providing this signal to low-frequency loudspeakers, allowing for flexible loudspeaker arrangements and reduced costs by using fewer subwoofers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wave-field synthesis is implemented with a large number of loudspeakers to achieve accurate spatial sound reproduction, then the spatial impression and directionality are improved, but the device complexity, cost, and difficulty of storage and management increase significantly
Solution Approach 1:
The patent extracts the low-frequency channel information from the multichannel audio signal and processes it separately through a dedicated low-pass filter. This separation allows the low-frequency reproduction to be handled independently, reducing the requirements for the overall loudspeaker system while maintaining accurate spatial reproduction for the full-frequency signal.
Solution Approach 2:
The audio signal is segmented into different frequency components, with the low-frequency channel being filtered and processed separately from the main multichannel signal. This segmentation enables independent optimization of low-frequency reproduction without affecting the spatial accuracy of the full-frequency signal.
2Device complexity
If the number of loudspeakers is reduced to lower costs and simplify management, then device complexity and storage requirements decrease, but level artefacts increase and spatial sound reproduction quality deteriorates
Solution Approach 1:
A dedicated low-pass filter is introduced as an intermediary component to process the low-frequency channel separately. This intermediary ensures that low-frequency reproduction remains accurate even when the overall number of loudspeakers is reduced, preventing level artefacts while simplifying the main loudspeaker system.
3Measurement precision
If low-frequency channels are generated for each individual loudspeaker in wave-field synthesis, then spatial accuracy is maintained, but the computational complexity and processing requirements increase dramatically
Solution Approach 1:
The patent merges the low-frequency channel generation into a single centralized processing path that feeds all loudspeakers uniformly. Instead of generating separate low-frequency channels for each loudspeaker, the low-pass filtered signal is distributed to all speakers, significantly reducing computational complexity while maintaining spatial accuracy through the original multichannel signal path.
Data Source
AI summary
For generating a low-frequency channel for a low-frequency loudspeaker arranged at a predetermined low-frequency loudspeaker position, a plurality of audio objects are initially provided, each audio object having an object position and an object description associated with it. Hereafter, a calculation of an audio object scaling value is performed for each audio object on the basis of the object description, so that an actual amplitude state at least comes close to a target amplitude state at a reference playback position. Thereafter, each object signal is scaled with an associated audio object scaling value so as to then sum the scaled object signals. From the composite signal obtained there, a low-frequency channel is subsequently derived for the low-frequency loudspeaker, and is provided to the respective low-frequency loudspeaker. Due to the scaling of the individual object signals of the audio objects, this approach is independent of an actual situation of a multichannel playback system with regard to the number and density of the loudspeakers as well as with regard to the size of the presentation area actually present.