Stereo Microphone Azimuth Elevation Localization
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Solution Overview
Problem
As the number of channels and speaker layouts in audio playback systems increases from 2D to 3D, accurately positioning and rendering sounds becomes increasingly complex, especially in home theater environments with height speakers, where existing methods rely on multiple microphones positioned at various locations for azimuthal and height information.
Innovation Solution
The use of a pair of coincident, vertically-stacked directional microphones, such as an XY stereo microphone system, to determine azimuthal and elevation angles of sound sources based on intensity and temporal differences between microphone signals, generating audio objects with metadata for precise sound source localization, and transforming this data into various coordinate systems using inertial sensor data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple microphones are positioned at various locations to capture azimuthal and height information, then sound source localization accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines both azimuthal and elevation angle determination capabilities into a single vertically-stacked microphone pair. By merging the functions of multiple microphones positioned at various locations into one compact coincident microphone system, the patent achieves accurate 3D sound source localization while reducing device complexity and the number of required microphones.
Solution Approach 2:
The patent transitions from traditional 2D stereo microphone positioning to 3D spatial audio capture by vertically stacking microphones. This dimensional change allows the system to capture both horizontal (azimuthal) and vertical (elevation) sound source information simultaneously from a single location, improving localization accuracy without proportionally increasing device complexity.
2Adaptability or versatility
If more channels and speaker layouts are added to audio playback systems, then sound immersion is improved, but rendering complexity increases
Solution Approach 1:
The patent creates a universal audio capture system that can serve multiple playback configurations (2D and 3D). The coincident vertically-stacked microphone system captures comprehensive spatial audio information that can be rendered to various speaker layouts, making the system adaptable to different playback environments without requiring separate recording systems for each configuration.
Solution Approach 2:
The patent extracts essential spatial audio information (azimuthal and elevation angles) from the complex multi-channel audio data using signal processing techniques. By separating and identifying the key spatial parameters from the full audio signal, the system simplifies the rendering process while maintaining the ability to support versatile playback configurations.
3Device complexity
If vertically-stacked directional microphones are used to determine azimuthal and elevation angles, then the number of microphones is reduced, but measurement precision may be compromised
Solution Approach 1:
The patent applies preliminary signal processing to the microphone signals, including upsampling and filtering operations, to enhance the precision of angle determination. By preparing and conditioning the audio signals before analysis, the system compensates for the limited physical separation of the coincident microphones, maintaining measurement precision while using fewer microphones.
Solution Approach 2:
The patent changes the processing parameters of the audio signals through upsampling and frequency domain transformations. These parameter changes enhance the resolution and accuracy of the cross-correlation analysis used to determine elevation angles, allowing precise measurement despite the compact microphone configuration.
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
Enables accurate and efficient sound source localization in complex playback environments with fewer microphones, improving sound localization and immersion by generating audio objects with precise spatial metadata, reducing the complexity of rendering sounds in multi-channel systems.
Implementation Method 1
determining, based at least in part on an intensity difference between the first microphone audio signals and the second microphone audio signals, an azimuthal angle corresponding to a sound source location
Implementation Method 2
determining, based at least in part on a temporal difference between the first microphone audio signals and the second microphone audio signals, an elevation angle corresponding to the sound source location
Data Source
AI summary
Input audio data, including first microphone audio signals and second microphone audio signals output by a pair of coincident, vertically-stacked directional microphones, may be received. An azimuthal angle corresponding to a sound source location may be determined, based at least in part on an intensity difference between the first microphone audio signals and the second microphone audio signals. An elevation angle corresponding to a sound source location may be determined, based at least in part on a temporal difference between the first microphone audio signals and the second microphone audio signals. Output audio data, including at least one audio object corresponding to a sound source, may be generated. The audio object may include audio object signals and associated audio object metadata. The audio object metadata may include at least audio object location data corresponding to the sound source location.