Stereo to Multi-Mono Conversion for Automotive Spatial Audio
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Solution Overview
Problem
In confined spaces like automobile cabins, the fidelity of auditory scenes is typically degraded due to deviations from ideal listening conditions, such as incorrect listening and loudspeaker positions, and the presence of reflecting surfaces, leading to a degradation in the reproduction of sound timbre and spatial attributes.
Innovation Solution
A stereo to multi-mono conversion method and device that estimates the location of phantom sources from binaural signals, allowing each loudspeaker to reproduce specific signal components within defined azimuthal angles, thereby making the auditory scene independent of the listening position and improving spatial sound reproduction across a larger area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stereo reproduction is used in automotive cabins, then the system complexity remains low with standard loudspeaker setups, but the auditory scene fidelity degrades due to deviations from ideal listening conditions
Solution Approach 1:
The invention segments the stereo signal into multiple monophonic components, each associated with specific spatial attributes. By decomposing the auditory scene into discrete sound sources with individual localization parameters, the system can process and reproduce each component through appropriate loudspeakers, thereby maintaining auditory scene fidelity without requiring a complete overhaul of the reproduction system architecture
Solution Approach 2:
The invention transforms the reproduction approach by changing from direct stereo signal playback to a parameter-based representation. Each sound source is characterized by parameters including azimuth angle, elevation angle, and distance, allowing the system to adapt the reproduction to actual listening conditions and compensate for deviations from ideal setup, thus improving fidelity without increasing hardware complexity
2Reliability
If standard stereo loudspeaker arrangement is used, then the system is simple to implement, but the spatial attributes reproduction degrades in confined spaces with reflecting surfaces
Solution Approach 1:
The invention performs preliminary analysis of the stereo signal to extract spatial parameters of sound sources before reproduction. By pre-determining the azimuth and elevation angles of each sound component, the system can strategically direct these components through appropriate loudspeakers, establishing accurate spatial reproduction before the harmful effects of reflections occur in the confined cabin environment
Solution Approach 2:
The invention applies different processing strategies to different sound components based on their spatial characteristics. Sound sources at different azimuth and elevation angles are reproduced through specifically selected loudspeakers, creating locally optimized reproduction zones that maintain spatial accuracy despite the presence of reflecting surfaces in the overall cabin environment
3Area of stationary object
If stereo signals are reproduced with matched loudspeaker pair in symmetrical arrangement, then the auditory scene is accurate at the optimal listening position, but the listening area coverage remains limited
Solution Approach 1:
The invention extends the reproduction capability by utilizing vertical dimension through ceiling-mounted loudspeakers in addition to the horizontal plane loudspeaker arrangement. By reproducing sound components with elevation angles through the ceiling loudspeaker, the system creates a three-dimensional auditory scene that maintains localization accuracy across a larger listening area, effectively adding another dimension to the reproduction space
Solution Approach 2:
The invention makes each loudspeaker serve multiple functions by assigning them specific spatial zones based on azimuth and elevation parameters. The front loudspeakers handle sound sources in the forward hemisphere, while the ceiling loudspeaker handles elevated sources, creating a universal system that can accurately reproduce sound sources from various positions in three-dimensional space, thereby expanding the effective listening area
Data Source
AI summary
Disclosed are methods for selecting auditory signal components for reproduction by means of one or more supplementary sound reproducing transducers, such as loudspeakers, placed between a pair of primary sound reproducing transducers, such as left and right loudspeakers in a stereophonic loudspeaker setup or adjacent loudspeakers in a surround sound loudspeaker setup. Also disclosed are devices for carrying out the above methods and systems of such devices.