Audio Rattle Mitigation via Spectral Attenuation
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Solution Overview
Problem
Computing devices like laptops and tablets experience mechanical rattle due to mechanical resonance caused by low-frequency energy leakage from speakers, leading to audible distortion and reduced audio fidelity.
Innovation Solution
A system comprising a processing subsystem and an analyser subsystem that selectively applies an attenuation function to the input audio signal based on its spectral content, using a classifier and filters to mitigate mechanical rattle by reducing signal components at rattle-causing frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mid-band attenuation is applied to reduce distortion, then speaker distortion is reduced, but overall volume is perceived as reduced and sound is colored
Solution Approach 1:
The patent segments the frequency spectrum into specific bands (low-frequency 20-200Hz, mid-frequency 200-2000Hz, high-frequency 2000-20000Hz) and applies different processing to each band. This allows targeted attenuation of rattle-causing frequencies without broad mid-band attenuation that would reduce overall volume and color sound.
Solution Approach 2:
The patent applies local quality by using different attenuation levels for different frequency bands based on the detected rattle frequency. The system applies maximum attenuation at the rattle frequency, reduced attenuation at adjacent frequencies, and no attenuation at other frequencies, preserving audio fidelity while eliminating rattle.
2Device complexity
If mechanical coupling is used to mount speakers, then device structure is simplified, but mechanical resonance and rattle occur
Solution Approach 1:
The patent replaces mechanical solutions (such as complex mounting structures or dampers) with an electronic signal processing solution. The system detects rattle frequencies and applies electronic attenuation to the audio signal, eliminating mechanical resonance without adding mechanical complexity.
3Object-affected harmful factors
If broad frequency attenuation is applied, then distortion is reduced, but audio fidelity is reduced due to volume reduction and sound coloring
Solution Approach 1:
The patent implements dynamic frequency-dependent attenuation where the attenuation level for each frequency band is adjusted in real-time based on the detected rattle frequency and the spectral content of the input signal. This dynamic approach preserves audio fidelity by applying attenuation only when and where needed.
Solution Approach 2:
The patent changes the attenuation parameter selectively across different frequency bands and over time based on the detected rattle characteristics. The system adjusts attenuation levels dynamically, applying maximum attenuation at rattle frequencies while maintaining lower attenuation at other frequencies to preserve audio quality.
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
Effectively reduces mechanical rattle and associated distortion, improving audio fidelity by applying targeted attenuation to specific frequency components, while minimizing volume reduction and unwanted sound coloring.
Implementation Method 1
an audio output transducer (110) of the computer, wherein the processing subsystem is configured to selectively apply an attenuation function to an input audio signal to attenuate a signal component of the input audio signal at a frequency that causes mechanical rattle
Implementation Method 2
mechanical resonance of the whole or part of the device to which the transducer is mechanically coupled, generating secondary noise
Implementation Method 3
the processing subsystem is configured to selectively apply an attenuation function to the input audio signal to attenuate a signal component of the input audio signal at a frequency that causes mechanical rattle
Data Source
AI summary
A computer having a system for mitigating mechanical rattle arising due to a mechanical coupling of an audio output transducer to a part of the computer device, the system comprising: a processing subsystem configured to receive an input audio signal and to output a drive signal for driving the audio output transducer to produce a transducer output, wherein the processing subsystem is configured to selectively apply an attenuation function to the input audio signal to attenuate a signal component of the input audio signal at a frequency that causes mechanical rattle in the computer; and an analyser subsystem configured to receive the input audio signal and to output a control signal to the processing subsystem to control application of the attenuation function to the input audio signal by the processing subsystem based on a spectral content of the received input audio signal; wherein the attenuation function is based on characteristic acoustic behaviour of the computer.