Speaker Audio Masking to Reduce Rattle Distortion
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Solution Overview
Problem
Speakers introduce distortion, particularly mechanical rattle, due to design and manufacturing trade-offs, which existing solutions often address inadequately, leading to undesirable volume limitations and sound pressure level losses.
Innovation Solution
A method and apparatus that attenuate specific frequency bands of an audio signal to minimize distortion, generating masking audio through harmonics to psychoacoustically replace attenuated content, thereby reducing perceived distortion and maintaining sound pressure levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the volume of audio within middle frequencies is limited to reduce mechanical rattle, then speaker distortion is reduced, but sound pressure level is noticeably reduced
Solution Approach 1:
The patent generates harmonics from the attenuated middle frequency content and uses them to mask the distortion. The harmful attenuation is converted into a benefit by creating new frequency components that psychoacoustically replace the original content, maintaining perceived sound pressure level while eliminating mechanical rattle
Solution Approach 2:
The patent introduces harmonics as an intermediary element between the attenuated middle frequency content and the listener's perception. These harmonics serve as a mediator that preserves the perceived audio quality and sound pressure level while allowing the problematic middle frequency content to be reduced
2Volume of moving object
If smaller speakers are used to meet space constraints, then device size is reduced, but audio reproduction accuracy deteriorates
Solution Approach 1:
The patent replaces the mechanical limitation of small speakers with a digital signal processing solution. Instead of relying on the physical speaker to reproduce all frequencies accurately, the system uses electronic attenuation and harmonic generation to compensate for the speaker's inability to reproduce certain frequencies without distortion
Solution Approach 2:
The patent changes the frequency distribution parameters of the audio signal by attenuating specific frequency bands and generating harmonics. This transforms the spectral content to match the capabilities of small speakers while maintaining perceived audio quality through psychoacoustic masking
3Object-affected harmful factors
If attenuation is applied to distortion-producing frequency bands, then perceived distortion is reduced, but sound pressure level is reduced
Solution Approach 1:
The patent converts the harmful effect of attenuation (reduced sound pressure level) into a benefit by generating harmonics that psychoacoustically mask the attenuation. The loss of energy in the original frequency band is compensated by the energy of the generated harmonics, which the human ear perceives as filling in the missing content
Solution Approach 2:
The patent applies periodic harmonic generation based on the attenuated signal content. By generating harmonics at integer multiples of the original frequency components, the system creates a periodic structure that naturally masks the attenuation through psychoacoustic effects, maintaining perceived sound pressure level
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 perceived audio distortion in speakers by attenuating distortion-producing frequency bands and augmenting with harmonics, masking the distortion and offsetting sound pressure level losses, enhancing audio quality without noticeable volume reduction.
Implementation Method 1
attenuating the input audio signal within an attenuation frequency band of the input audio signal to generate a limited audio signal
Implementation Method 2
generating masking audio to psychoacoustically mask absence of audio content attenuated from the attenuation frequency band
Implementation Method 3
generating masking audio to psychoacoustically mask absence of audio content attenuated from the attenuation frequency band
Implementation Method 4
combining the limited audio signal and the masking audio to generate an output audio signal
Data Source
AI summary
A method for reducing perceived audio distortion in a loudspeaker in response to an input audio signal may include attenuating the input audio signal within an attenuation frequency band of the input audio signal to generate a limited audio signal, generating masking audio to psychoacoustically mask absence of audio content attenuated from the attenuation frequency band of the input audio signal, and combining the limited audio signal and the masking audio to generate an output audio signal.