Loudspeaker Array Signal Generation for Spatial Audio
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Solution Overview
Problem
Conventional spatial audio reproduction methods, such as wave field synthesis and Ambisonic, face limitations in computing power and spatial resolution, especially when dealing with multiple moving sound sources, leading to increased complexity and cost constraints in consumer applications.
Innovation Solution
The method involves using wave field synthesis to simulate static virtual sound waves, which are then adapted to the reproduction format, allowing for the exploitation of higher spatial resolution while keeping computing expenditure constant by representing sources as static or semi-static, and using a hybrid approach with Ambisonic to reduce computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wave field synthesis is used to reproduce multiple moving sound sources, then spatial resolution and sound field accuracy are improved, but computing power requirements increase tremendously
Solution Approach 1:
The patent segments the sound reproduction task into two stages: a prestage that generates a reduced number of output audio signals using virtual sources, and a main stage that processes these signals through a loudspeaker array. This segmentation reduces the computational complexity by breaking down the complex problem of reproducing multiple moving sources into manageable stages, where the prestage handles source mapping and the main stage handles spatial distribution.
Solution Approach 2:
The patent introduces virtual sources as intermediary elements that map input audio signals to loudspeaker positions. These virtual sources act as mediators between the actual sound sources and the loudspeaker array, simplifying the computational process by creating an intermediate representation that reduces the number of calculations required for spatial audio reproduction.
2Manufacturing precision
If the number of loudspeakers in the array is increased, then wave field synthesis capabilities are improved, but computing effort increases tremendously
Solution Approach 1:
The patent performs preliminary processing in the prestage by generating output audio signals that are specifically prepared for the loudspeaker array. This preliminary action includes mapping virtual sources to loudspeaker positions and pre-calculating spatial distribution parameters, which reduces the computational effort required during the main processing stage and eliminates the need for complex real-time calculations.
Solution Approach 2:
The patent changes the parameters of the audio signals by transforming them from the virtual source domain to the loudspeaker domain. This parameter transformation includes adjusting amplitude, phase, and timing parameters to match the specific configuration of the loudspeaker array, thereby optimizing the sound field reproduction while managing computational complexity.
3Measurement precision
If Ambisonic order is increased to achieve higher spatial resolution, then sound field accuracy is improved, but system complexity increases and requires sophisticated microphone arrays
Solution Approach 1:
The patent creates a virtual copy of the loudspeaker array in the form of virtual sources that replicate the spatial characteristics of the actual loudspeakers. This virtual model allows for simplified processing by working with a reduced set of output signals that capture the essential spatial information without requiring the full complexity of high-order Ambisonic systems or sophisticated microphone arrays.
Data Source
AI summary
An apparatus for generating a number of loudspeaker signals for a loudspeaker array defining a reproduction space includes a prestage configured to generate a plurality of output audio signals while using one or more audio signals associated with one or more virtual positions, each output audio signal being associated to a loudspeaker position such that the plurality of output audio signals together replicate a reproduction of the input audio signal(s) at the virtual position(s), and a number of output audio signals being smaller than a number of loudspeaker signals. The apparatus further includes a main stage configured to obtain the plurality of output audio signals and further to obtain, as a virtual position for each output audio signal, the loudspeaker positions, and to generate the number of loudspeaker signals for the loudspeaker array such that the loudspeaker positions are replicated as a virtual sources by the loudspeaker array.