Dynamic Notch Filter for Speaker Buzzing Suppression
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Solution Overview
Problem
Modern hand-held electronic devices face challenges in achieving high-quality sound due to buzzing noises caused by mechanical and acoustic resonances in small speaker designs, which are amplified by the speaker port resonance, affecting user experience.
Innovation Solution
Implementing a processing device with dynamic notch filtering that selectively suppresses buzzing harmonics by analyzing the audio content and adjusting the filter's strength and width to minimize distortion, using calibration data to determine optimal settings for reducing mechanical rattling and port resonance amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the speaker volume is increased to meet customer expectations for sound quality, then the sound output is improved, but buzzing noise is generated due to mechanical and acoustic resonances
Solution Approach 1:
The patent identifies the resonant frequencies that cause buzzing and uses dynamic notch filtering to selectively attenuate only those specific frequency components while preserving the rest of the audio spectrum. This converts the harmful resonance effect into a manageable parameter by targeting only the problematic frequencies rather than reducing overall volume
Solution Approach 2:
The system dynamically adjusts the notch filter parameters (center frequency and bandwidth) based on real-time spectral analysis of the audio signal. This allows the filter to adapt to varying audio content and resonant conditions, maintaining sound quality while suppressing buzzing across different volume levels and audio types
2Object-generated harmful factors
If a static notch filter is used to suppress buzzing at resonant frequencies, then buzzing is reduced, but significant portions of the audio signal are also suppressed
Solution Approach 1:
The patent transitions from a static notch filter with fixed parameters to a dynamic notch filter whose center frequency and bandwidth are continuously adjusted based on spectral analysis of the audio signal. This dynamic adaptation allows the filter to precisely track resonant frequencies and minimize attenuation of non-resonant audio content
Solution Approach 2:
The dynamic notch filter applies attenuation selectively only at the identified resonant frequency components while leaving the rest of the audio spectrum unaffected. This localized filtering approach ensures that only the problematic buzzing frequencies are suppressed without degrading the overall audio quality
3Volume of moving object
If the speaker size is reduced to fit hand-held devices, then device portability is improved, but mechanical resonances are amplified causing buzzing
Solution Approach 1:
The patent introduces a signal processing intermediary (dynamic notch filter) between the audio source and the speaker. This intermediary analyzes the audio spectrum, identifies resonant frequencies, and applies selective attenuation, thereby mediating the interaction between the audio signal and the speaker's mechanical resonances without requiring physical modifications to the speaker design
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
Significantly reduces buzzing noise without detrimental suppression of the audio signal, enhancing user experience by masking unwanted harmonics with strong spectral content, and dynamically adapting to varying audio conditions.
Implementation Method 1
a spectral density of the audio content at or near a first frequency fb associated with a mechanical resonance of the speaker is determined; and a spectral density of the audio content at or near a second frequency fp associated with an acoustic port resonance of an opening of the speaker is determined
Implementation Method 2
a dynamic notch filter may then be configured with adjustable settings or parameters to limit the audio content at or near the frequency of the mechanical resonance, fb, to an extent sufficient to mask the buzzing
Implementation Method 3
A signal having an audio content may then be provided to a speaker to convert the audio content of the signal into a sound
Implementation Method 4
an acoustic port resonance of an opening of the speaker is determined
Data Source
AI summary
The implementations describe a method and a system to perform the method to reduce buzzing in a speaker by obtaining a signal having an audio content, determining a first value of spectral density of the audio content at a first resonance frequency, the first resonance frequency associated with a mechanical motion of at least one member of a speaker assembly, determining a second value of spectral density of the audio content at a second resonance frequency, the second resonance frequency associated with a port of the speaker assembly, determining, responsive to the first value and the second value, that the signal is to produce buzzing of the speaker at the second resonance frequency, producing a modified signal by limiting spectral density of the audio content at the first resonance frequency, and providing the modified signal to the speaker.