Adaptive Noise Reduction Circuitry for Communication Apparatus
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Solution Overview
Problem
Existing ambient noise-reduction systems for communications devices, such as cellular phone handsets, fail to effectively account for the change in sound environment when using separate listening devices, requiring different noise-sensing and signal-processing approaches that are not adequately addressed by current technologies.
Innovation Solution
The implementation of a noise reduction circuitry that automatically switches between internal and external modes, using multiple microphones and signal processing to generate a noise cancellation signal that matches the ambient noise characteristics, and incorporates identification mechanisms for different listening devices to adjust signal processing parameters accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If ambient noise reduction is provided using a fixed signal processing approach, then the system structure is simple, but the noise reduction effectiveness deteriorates when switching between internal speaker and external listening devices
Solution Approach 1:
The patent implements dynamic switching between two distinct signal processing modes (internal mode and external mode) based on the detected listening device state. The system automatically selects the appropriate transfer function and processing parameters according to whether an external listening device is connected, ensuring optimal noise reduction performance for each mode while maintaining a relatively simple overall system structure.
Solution Approach 2:
The patent changes key signal processing parameters including the transfer function characteristics, microphone signal combination ratios, and noise cancellation algorithm parameters depending on the operating mode. By adjusting these parameters based on the detected listening device type, the system achieves effective noise reduction for both internal speaker and external listening device scenarios without requiring completely different system architectures.
2Reliability
If separate noise reduction systems are provided for internal and external modes, then noise reduction effectiveness is improved for each mode, but device complexity increases
Solution Approach 1:
The patent designs a universal noise reduction system that handles both internal speaker mode and external listening device mode through a single integrated signal processing chain. The system uses a common set of microphones, a unified transfer function calculation mechanism, and a single noise cancellation output path that adapts its parameters based on the operating mode, thereby achieving multi-functionality without duplicating entire subsystems.
Solution Approach 2:
The patent employs dynamic mode detection and switching logic that monitors the listening device state and automatically configures the appropriate signal processing parameters. This dynamic adaptation allows one noise reduction system to effectively serve multiple functions (internal mode and external mode) by changing its operational characteristics rather than requiring separate dedicated systems for each mode.
3Ease of operation
If the system automatically detects listening device type, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The patent implements a self-service detection mechanism where the noise reduction system automatically monitors its own operational state by detecting the presence or absence of external listening devices through the existing audio interface circuitry. The system self-determines whether it is in internal mode or external mode based on electrical connections and acoustic feedback, eliminating the need for separate user input devices or complex external sensors while maintaining automatic mode switching capability.
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 solution provides effective ambient noise reduction in both internal and external modes, ensuring optimal noise reduction performance regardless of the listening device used, enhancing user experience and convenience by integrating noise-reduction signal-processing into the handset, reducing bulkiness and cost, and allowing user-adjustable noise reduction settings.
Implementation Method 1
detecting sounds other than the sound to be listened to using a first transducer means
Implementation Method 2
generates a sound that tends to cancel the effect of the ambient noise at the ear of the user
Data Source
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AI summary
Noise reduction circuitry for a communication apparatus can apply different noise reduction transfer functions, depending on whether a listening device is connected to the apparatus. If no listening device is connected, the noise reduction transfer function can be adapted for use with microphones and speakers that form an integral part of the communication apparatus, which may be a cellular telephone. If a listening device is connected, the noise reduction transfer function can be adapted for use with microphones and speakers that form a part of the listening device. This allows the noise reduction circuitry to provide improved noise reduction performance.