Audio Signal Processing Apparatus for Directional Rendering
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Solution Overview
Problem
Existing audio signal processing technologies face challenges in generating an output audio signal with directivity using omni-directional microphones, particularly in maintaining low-frequency band quality and aligning microphone arrays with imaging apparatuses in head-mounted displays, which results in tone color distortion and increased system costs.
Innovation Solution
An audio signal processing method and apparatus that utilizes a plurality of omni-directional sound collecting devices to generate an output audio signal by determining the incidence direction for each frequency component based on cross-correlations between input audio signals, allowing for directional pattern rendering and reducing low-frequency band loss by decomposing signals into low and high-band components and applying specific gains to each frequency component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a first-order ambisonic microphone is used to analyze the sound field, then the sound field analysis capability is improved, but the array size increases and misalignment with the camera center occurs
Solution Approach 1:
The patent uses an omni-directional microphone to capture the sound field and then creates a virtual first-order ambisonic microphone signal through signal processing. Instead of physically implementing a large first-order ambisonic microphone array, the system copies the functional capability of such an array by processing the omnidirectional signal to generate directional patterns mathematically, thereby achieving the same sound field analysis capability without the physical size constraints.
2Measurement precision
If a cardioid microphone is used to provide directivity, then the directivity performance is improved, but the system cost increases
Solution Approach 1:
The patent replaces the mechanical/directional property of cardioid microphones with a signal processing approach. Instead of using expensive directional microphones that have built-in directivity through their physical design, the system uses an inexpensive omni-directional microphone and generates directional patterns through digital signal processing (beam forming and deconvolution), substituting mechanical directivity with computational directivity.
3Measurement precision
If time delay-based beam forming is used to detect sound source location, then the location detection capability is improved, but tone color distortion occurs due to phase inversion in low-frequency band
Solution Approach 1:
The patent applies deconvolution processing as a preliminary step before beam forming to correct phase inversion issues in the low-frequency band. By pre-processing the omnidirectional signal to compensate for phase distortions, the system ensures that subsequent beam forming operations work with corrected signals, thereby maintaining both location detection accuracy and audio signal quality without the tone color distortion problems.
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
The method effectively provides an output audio signal with directivity using omni-directional microphones, reducing low-frequency band loss and achieving sound image localization similar to directional microphone arrays, while maintaining cost-effectiveness and compatibility with imaging apparatuses.
Implementation Method 1
obtains an incidence direction for each frequency component for at least some frequency components of each of the plurality of input audio signals based on cross-correlations between the plurality of input audio signals
Data Source
AI summary
An audio signal processing apparatus for rendering an input audio signal is disclosed. The audio signal processing apparatus includes a receiving unit, which obtains a plurality of input audio signals corresponding to sounds collected by each of a plurality of sound collecting devices, a processor, which obtains an incidence direction for each frequency component for at least some frequency components of each of the plurality of input audio signals corresponding to a sound incident to each of the plurality of sound collecting devices based on cross-correlations between the plurality of input audio signals, and generates an output audio signal by rendering at least some of the plurality of input audio signals based on the incidence direction for each frequency component, and an output unit, which outputs the generated output audio signal.