Networked Microphone Direction Determination via Audio Phase Offset
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Solution Overview
Problem
Existing media playback systems face challenges in accurately determining the direction of a networked microphone device (NMD) relative to audio playback devices, which affects calibration and control operations, especially in environments with varying acoustic characteristics.
Innovation Solution
The system uses recorded audio content from two audio drivers to determine the phase offset and relative distances, allowing for geometric calculation of the NMD's direction, enabling precise calibration and control adjustments based on the NMD's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the system uses recorded audio content from two audio drivers to determine phase offset and relative distances for geometric calculation of NMD direction, then the measurement precision of NMD direction is improved, but the device complexity increases due to requiring multiple audio drivers and complex geometric calculations
Solution Approach 1:
The system divides the audio playback function into multiple independent audio drivers (e.g., left and right speakers) that can be individually controlled and measured. Each audio driver acts as a separate sound source, allowing the system to perform multiple measurements and calculate directional information through geometric relationships between the segmented sound sources and the NMD.
Solution Approach 2:
The system introduces audio content as an intermediary medium to establish spatial relationships. By playing recorded audio content through multiple audio drivers and having the NMD record the playback, the system creates measurable acoustic paths that serve as intermediaries for calculating phase offsets, relative distances, and directional angles without requiring direct sensor-to-device line-of-sight or complex hardware modifications.
2Adaptability or versatility
If the system performs calibration and control adjustments based on NMD position, then the adaptability to environmental acoustic characteristics is improved, but the time required for calibration and setup increases
Solution Approach 1:
The system performs calibration measurements and determines NMD directional information during the initial setup phase. By conducting the audio playback through multiple drivers and recording the environmental responses in advance, the system establishes baseline calibration data that enables rapid adaptation to the specific acoustic environment without requiring time-consuming adjustments during actual use.
Solution Approach 2:
The system uses the NMD's recorded audio content as feedback to determine phase offsets and calculate directional relationships. This feedback mechanism allows the system to automatically adjust and adapt to the environmental acoustic characteristics by continuously monitoring the audio responses and refining the calibration parameters based on the measured phase differences and geometric calculations.
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 improves the accuracy of audio output adjustments and enhances the listening experience by accounting for the NMD's position relative to the playback devices, leading to better synchronization and environmental adaptation.
Implementation Method 1
determine a phase offset between the two audio drivers based on the recorded audio content
Implementation Method 2
determine relative distances between the two audio drivers and the NMD, based on the determined phase offset and a known speed of sound
Data Source
AI summary
Example techniques involve determining a direction of an NMD. An example implementation includes causing two audio drivers to output audio content, where the audio drivers are positioned at a known distance apart in a given azimuthal plane and recording the audio content output by the two audio drivers. The implementation also includes causing a computing device to identify a direction of the NMD relative to a center point of the two audio drivers in the given azimuthal plane. Identifying the direction of the NMD may involve determining a range of possible azimuthal angles between the NMD and the center point, the range of possible angles dependent upon the known distance between the two audio drivers and a phase offset between the two audio drivers indicated by the recorded audio content output. The implementation further includes causing a playback device to adjust calibration based on the identified direction of the NMD.