Microphone Array Level Control for Consistent Gain Across Channels
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Solution Overview
Problem
In microphone array systems, independent automatic level control (ALC) functions across multiple devices can lead to inconsistent gain adjustments, which complicates post-processing tasks like voice orientation/localization and noise cancellation, as each device may apply different amounts of gain, resulting in normalized signals that can hinder these processes.
Innovation Solution
A distributed automatic level control system where each microphone device receives and produces a common automatic level control parameter based on aggregated data from other devices, ensuring consistent gain adjustments across the array, thereby normalizing all signals to a common level and facilitating coordinated ALC functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If independent automatic level control is implemented across multiple microphone devices, then each device can dynamically adjust its signal level, but inconsistent gain adjustments occur across the array
Solution Approach 1:
The patent merges the ALC functions of multiple independent microphone devices into a coordinated system. Each device receives a common ALC parameter from a lead device, ensuring that all devices apply the same gain adjustment simultaneously. This combines previously independent control functions into a unified system that maintains signal level consistency across the microphone array.
Solution Approach 2:
The system implements feedback by having the lead device monitor the overall signal levels from all microphone devices and adjust the common ALC parameter accordingly. This feedback loop ensures that the coordinated ALC response maintains consistent signal levels across the array while adapting to changing acoustic conditions.
2Ease of operation
If each microphone device applies different amounts of gain independently, then local signal normalization is achieved, but post-processing tasks like voice orientation and noise cancellation are hindered
Solution Approach 1:
The patent merges the ALC operations of all microphone devices into a coordinated response led by a lead device. Instead of each device independently normalizing its signal, all devices receive and apply the same common ALC parameter, ensuring that signal normalization occurs uniformly across the array. This preserves the relative amplitude relationships needed for voice orientation and noise cancellation processing.
3Stability of the object's composition
If a centralized ALC system is used to ensure consistent gain adjustments, then signal normalization is improved, but system complexity increases
Solution Approach 1:
The patent segments the ALC system into a lead device that performs the complex parameter calculation and distribution, and follower devices that simply receive and apply the common parameter. This segmentation centralizes the computational complexity in one device while keeping the follower devices simple, achieving consistent gain adjustments without proportionally increasing the complexity of each individual device.
Solution Approach 2:
The lead device acts as an intermediary that coordinates the ALC parameters between the external environment and the follower microphone devices. It receives signal level information from all devices, calculates the appropriate common ALC parameter, and distributes it to all followers, simplifying the overall system architecture while ensuring consistent behavior.
Data Source
AI summary
A distributed automatic level control function is provided, in which information relating to a common automatic level control parameter is transmitted to each of a plurality of microphone devices, wherein the information transmitted to at least one microphone device is derived from an audio sample of at least one different microphone device. Each microphone device produces the common automatic level control parameter based on the information received by the microphone device and applies the common automatic level control parameter produced by the microphone device to a distributed automatic level controller of the microphone device.