Audio Source Localization via Amplitude Normalization
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Solution Overview
Problem
Determining the accurate location of an audio source is challenging, especially when the audio signal characteristics are highly variable, such as in speech, due to non-stationary amplitudes, which complicates processing operations in electronic devices like augmented reality and virtual reality headsets.
Innovation Solution
The audio system normalizes audio signals by estimating and combining amplitudes across time segments to create a stationary signal, allowing for more accurate localization using microphone array motion, even with non-stationary audio sources like speech.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If audio signals with non-stationary amplitudes (such as speech) are directly processed for localization, then the processing can be performed without additional transformation steps, but the localization accuracy deteriorates due to highly variable audio signal characteristics
Solution Approach 1:
The patent applies preliminary action by normalizing the audio signal amplitudes before performing localization processing. The system estimates amplitudes at multiple time points, normalizes the signal by these amplitudes, and then proceeds with localization operations on the normalized signal. This preprocessing step ensures that subsequent localization algorithms receive stationary signals, improving measurement precision without requiring fundamentally more complex processing architectures.
Solution Approach 2:
The patent changes the amplitude parameter of the audio signal through normalization. By estimating amplitudes at different time points and dividing the signal by these amplitude estimates, the system transforms the non-stationary signal into a stationary normalized signal. This parameter transformation maintains the directional information while removing amplitude variability, thereby improving localization accuracy.
2Measurement precision
If the audio system normalizes signals by estimating and combining amplitudes across time segments, then localization accuracy improves for non-stationary signals, but the processing time and computational complexity increase
Solution Approach 1:
The patent applies segmentation by dividing the audio signal into multiple time segments and estimating amplitudes at discrete time points within each segment. Rather than processing the entire signal as one block, the system normalizes each segment independently using amplitude estimates from that segment, then combines the normalized segments. This segmentation approach reduces computational complexity compared to analyzing the entire signal at once, while still capturing the non-stationary characteristics.
Solution Approach 2:
The patent uses partial action by estimating amplitudes at selected time points rather than continuously throughout the signal. The system normalizes the signal using amplitude estimates from specific time segments, which is sufficient to capture the essential non-stationary behavior without requiring exhaustive analysis of every instantaneous amplitude variation. This partial normalization achieves good localization accuracy with reduced computational effort.
Data Source
AI summary
An electronic device localizes an audio source by normalizing an amplitude of an audio signal over a time period. The electronic device receives, from one or more microphones of the electronic device, signal(s) representative of audio emitted by an audio source over a time period. The electronic device estimates amplitudes of the signal(s) at a first time within the time period and at a second time within the time period, where the second time is different from the first time. The electronic device normalizes the amplitudes associated with the first and second times to generate normalized amplitudes. The electronic device determines a combined amplitude representative of the audio emitted by the audio source by combining the normalized amplitudes. The electronic device determines, based at least in part on the combined amplitude and motion of the electronic device, an estimated position of the audio source relative to the electronic device.