Sound Source Direction Determination Using Dynamic Thresholds
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Solution Overview
Problem
Existing sound-source-direction determining apparatuses using directional microphones are larger and more costly due to the size of directional microphones, which limits their accuracy and practicality, especially when determining the direction of a sound source near a wearer's body.
Innovation Solution
A sound-source-direction determining apparatus using omnidirectional microphones with a first and second sound path, where the microphones are disposed at the ends of these paths with openings on intersecting flat surfaces, and a processor that updates a reference threshold based on sound pressure differences to determine the sound source direction, regardless of the gap size between the terminal and the wearer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If directional microphones are used to determine sound source direction, then the accuracy of direction determination is improved, but the size and cost of the apparatus increase
Solution Approach 1:
The apparatus divides the sound detection function into multiple omnidirectional microphones positioned at different locations (first microphone in first sound path, second microphone in second sound path) rather than using a single directional microphone. This segmentation allows the system to achieve direction determination capability through spatial distribution of simple omnidirectional microphones, avoiding the need for complex directional microphone structures.
Solution Approach 2:
The patent combines multiple omnidirectional microphones with sound path structures that have openings at intersecting flat surfaces. By merging the positional arrangement of microphones with the geometric configuration of sound paths, the system achieves direction determination functionality that would otherwise require directional microphones, thereby reducing size while maintaining accuracy.
2Measurement precision
If directional microphones are used to determine sound source direction, then the accuracy of direction determination is improved, but the cost of the apparatus increases
Solution Approach 1:
The patent replaces expensive directional microphones with multiple inexpensive omnidirectional microphones. Omnidirectional microphones are generally cheaper to manufacture and do not have the complex internal structures of directional microphones. By using multiple simple units rather than one complex unit, the overall cost is reduced while maintaining the direction determination capability.
3Device complexity
If a fixed reference threshold is used for direction determination, then the device complexity is reduced, but the accuracy deteriorates when gap size varies between terminal and wearer
Solution Approach 1:
The reference threshold is changed from a fixed value to a dynamic value that adapts to different operating conditions. The threshold is adjusted based on the sound pressure level of synthesized sound output, allowing the system to maintain high accuracy across varying gap sizes between the terminal and wearer. This dynamic adjustment compensates for changes in acoustic environment without requiring complex recalibration procedures.
Solution Approach 2:
The system uses feedback from the sound pressure level measurement to adjust the reference threshold. By monitoring the sound pressure level of synthesized sound output and using this information to update the threshold, the system automatically adapts to changing conditions, maintaining determination accuracy without increasing operational complexity for the user.
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 configuration increases the accuracy of determining the sound source direction using omnidirectional microphones, reducing the likelihood of erroneous determinations due to varying gap sizes between the terminal and the wearer, while minimizing the apparatus's size and cost.
Implementation Method 1
a first sound path having a first end and a second end and a second sound path having a first end and a second end, the first sound path having, at the first end thereof, a first opening that is open at a first flat surface, sound propagating through the first sound path from the first opening, the second sound path having, at the first end thereof, a second opening that is open at a second flat surface intersecting with the first flat surface, sound propagating through the second sound path from the second opening
Data Source
AI summary
A sound-source-direction determining apparatus includes a processor that updates a reference threshold such that the reference threshold increases as a sound pressure difference increases, the sound pressure difference being a difference between sound pressure of a certain frequency component of sound acquired by the first microphone and sound pressure of the certain frequency component of the sound acquired by the second microphone when the synthesized sound is output from the speaker and determines a direction in which a sound source of sound is located, based on comparison between the reference threshold and a sound pressure difference between sound pressure of a certain frequency component of the sound acquired by the first microphone and sound pressure of the certain frequency component of the sound acquired by the second microphone when the synthesized sound is not output from the speaker.