Asymmetric Acoustic Element for Audio Source Position Estimation
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Solution Overview
Problem
Existing two-microphone setups for audio source position determination are limited by symmetry, allowing only angular direction estimation within a 180-degree range, failing to differentiate between sound source positions and their symmetric counterparts, and require synchronization with the audio source, making practical applications impractical.
Innovation Solution
Incorporating an asymmetric acoustic element that provides a predictable acoustic effect to break symmetry, allowing the estimation of sound source positions by analyzing the degree to which the microphone signal matches expected acoustic characteristics in different areas, enabling selection between possible positions based on acoustic effect measures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If two microphones are used for position determination, then the cost and complexity are reduced, but the system becomes completely symmetric around the axis interconnecting the microphones, creating ambiguity in determining the angular direction beyond 180 degrees
Solution Approach 1:
The patent introduces an asymmetric acoustic element (such as an acoustic lens or reflector) positioned near one of the microphones to break the symmetry of the two-microphone system. This asymmetric element creates different acoustic paths for sounds arriving from different directions, allowing the system to distinguish between angles greater than 180 degrees while maintaining the simplicity of a two-microphone configuration.
2Measurement precision
If time of arrival calculation is used for position determination, then specific positions can be determined, but synchronization with the audio source is required, making practical applications impractical
Solution Approach 1:
The patent extracts and eliminates the synchronization requirement by using only time difference of arrival (TDOA) measurements between the two microphones rather than absolute time of arrival. By focusing on the relative time difference between microphone signals and incorporating asymmetric acoustic elements, the system achieves position determination without needing to synchronize with the audio source transmission time.
3Measurement precision
If asymmetric acoustic elements are added to break symmetry, then position determination accuracy is improved, but device complexity increases
Solution Approach 1:
The patent employs simple, inexpensive asymmetric acoustic elements such as acoustic lenses or reflectors that can be easily manufactured and positioned near the microphones. These elements provide the necessary symmetry breaking without requiring complex electronic processing or multiple additional microphones, thus improving position determination accuracy while minimizing increases in device complexity and cost.
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
This approach enhances position determination accuracy and flexibility, resolving ambiguity and reducing computational complexity, allowing reliable selection between possible positions without requiring synchronization with the audio source.
Implementation Method 1
an acoustic element providing an acoustic effect to sound from sound source positions to the first microphone
Data Source
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AI summary
An apparatus for determining a position estimate for an audio source comprises two microphones (M1, M2) and an acoustic element (203) providing an acoustic effect to sound from sound source positions to the first microphone (M1). The acoustic effect is asymmetric with respect to an axis (201) between the microphones (M1, M2). A position circuit (305) estimates two possible positions on different sides of the axis for the sound source in response to time of arrivals at the microphones (M1, M2). An estimator (307) determines an acoustic effect measure being indicative of a degree to which an acoustic effect of the first microphone signal matches an expected characteristic of the acoustic effect for sound sources on one side of the axis (201). Another circuit (309) determines the position estimate by selecting between the two possible positions in response to the acoustic effect measure. The approach may resolve ambiguities in position determination associated with position determination based on time of arrival at two microphones.