Adaptive Noise Filtering for Cooling Fan Interference
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Solution Overview
Problem
Portable information handling systems face challenges in reducing acoustical noise interference from cooling fans, which affects microphone quality, especially when cooling fans are placed in proximity to microphones due to size constraints, leading to intermittent noise reduction effectiveness.
Innovation Solution
An adaptive noise reduction system that utilizes an audio processor to apply a library noise reduction filter in conjunction with an adaptive filter, which converges on noise patterns associated with cooling fan operation, and allocates additional processing resources for rapid adaptation to changes in fan speed, thereby reducing noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If cooling fan is placed in proximity to microphone to reduce system size, then system compactness is improved, but acoustical noise interference increases
Solution Approach 1:
The patent introduces noise reduction filters as an intermediary element between the cooling fan noise source and the microphone. The filters process the audio signal to eliminate fan noise while preserving speech, allowing the microphone to be positioned near the fan without direct noise contamination. This mediator approach resolves the contradiction by decoupling the physical proximity from acoustic interference.
Solution Approach 2:
The patent dynamically adjusts noise reduction filter parameters based on detected fan noise characteristics. By changing filter parameters (such as frequency response, gain, and adaptation rate) in response to varying fan speeds and noise profiles, the system maintains effective noise cancellation while allowing the microphone to operate in close proximity to the fan.
2Reliability
If noise reduction filters are used to reduce cooling fan noise impact, then audio quality is improved, but filter effectiveness becomes intermittent due to changing fan speeds
Solution Approach 1:
The patent implements dynamic noise reduction filtering where the filter characteristics continuously adapt to changing fan operating conditions. The system monitors fan speed variations and adjusts filter parameters in real-time, transforming a static filtering approach into a dynamic one that maintains effectiveness across varying thermal and operational conditions.
Solution Approach 2:
The patent employs feedback mechanisms where the system continuously monitors both the audio signal for noise characteristics and the fan operational state. This feedback information is used to adjust filter parameters adaptively, ensuring that the noise reduction remains effective even as fan speeds change during different thermal conditions or workload scenarios.
3Measurement precision
If adaptive filter is used to converge on noise patterns, then noise reduction precision is improved, but convergence time causes intermittent reduced effectiveness during fan speed changes
Solution Approach 1:
The patent applies preliminary noise reduction filtering before the adaptive filter fully converges. By using initial noise profiles or predefined filter settings based on expected fan operating conditions, the system provides immediate noise cancellation that bridges the gap during the adaptive filter's convergence period, preventing the intermittent effectiveness problem.
Solution Approach 2:
The patent employs a hybrid approach where both fixed noise reduction filters and adaptive filters operate simultaneously or in sequence. The fixed filter provides immediate partial noise reduction while the adaptive filter converges to provide more precise cancellation. This excessive action ensures continuous effective noise reduction throughout the convergence period.
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 system effectively filters out cooling fan noise within a three to four second convergence time, improving audio recording quality by using a combination of library and adaptive filters to address changing noise patterns, resulting in reduced interference during fan speed adjustments.
Implementation Method 1
An adaptive filter analyzes recorded audible sound electronic signals to define an adaptive noise reduction filter that filters out noise, such as audible noise associated with cooling fan operation
Implementation Method 2
A cooling fan provides cooling airflow across the CPU to reject excess thermal energy
Implementation Method 3
An audio processor receives cooling fan settings and selects a library noise reduction filter stored in association with the cooling fan setting to filter audible sounds captured by a microphone
Data Source
AI summary
An information handling system audio system includes a library of noise reduction filters associated with cooling fan speeds to isolate out cooling fan noise. Changed cooling fan settings communicated to the audio system trigger application of a library noise reduction filter for the selected cooling fan setting to isolate out cooling fan noise while an adaptive filter defines a noise reduction filter from recorded sounds. The library noise reduction filter reduces cooling fan noises during the time used to determine the adaptive noise reduction filter. In one embodiment, changes in cooling fan settings prioritize definition of noise reduction filters by the adaptive filter.