Vehicle Standing Wave Attenuation via Phase-Adjusted Anti-Noise
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Solution Overview
Problem
Existing sound damping technologies for vehicles face challenges in effectively attenuating standing waves in limited spaces without occupying significant space and adapting to fluctuating vibration conditions due to age degradation and changing excitation conditions.
Innovation Solution
A standing wave attenuation device comprising a closed loop system with an acoustic vibration input device, feedback comb filter, phase adjustment parts, and an acoustic vibration output device that cancels out standing waves by emitting sound waves with inverse phases, allowing for efficient noise reduction in vehicles without occupying excessive space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If long pipes are installed to attenuate standing waves at low frequencies, then the attenuation effect is improved, but the installation space requirement increases and the device becomes more complex
Solution Approach 1:
The patent replaces the mechanical pipe resonance system with an electronic signal processing system. Instead of using physical pipes that resonate at specific frequencies, the invention uses microphones to detect standing waves, processes the signals through digital signal processing (DSP) to generate anti-phase signals, and outputs these through speakers to cancel the standing waves. This substitution of mechanical resonance with electronic signal processing achieves the same attenuation effect without requiring long physical structures, thus solving the space constraint problem while maintaining effective standing wave cancellation.
Solution Approach 2:
The patent changes the approach from fixed physical parameters (pipe lengths determined by cabin dimensions) to adjustable electronic parameters (digital signal processing parameters). The system can adaptively adjust the frequency, phase, and amplitude of the anti-phase signals generated by the DSP based on real-time detection of standing wave characteristics. This allows the system to effectively attenuate standing waves across different frequencies and cabin configurations without requiring physical reconfiguration or long fixed-length pipes.
2Ease of manufacture
If pipes are fixed based on initial cabin dimensions, then the attenuation works for specific frequencies, but the system cannot adapt to fluctuating vibration conditions due to age degradation and changing excitation conditions
Solution Approach 1:
The patent transforms the static, fixed pipe system into a dynamic, adaptive electronic system. The microphones continuously detect the current standing wave characteristics in the cabin, and the digital signal processing unit dynamically adjusts the anti-phase signals in real-time. This allows the system to adapt to changing vibration conditions, age-related degradation, and different excitation frequencies without requiring physical reconfiguration. The electronic parameters (frequency, phase, amplitude) can be continuously adjusted to match the current acoustic environment, providing ongoing effectiveness as vehicle conditions change over time.
Solution Approach 2:
The patent implements a feedback control system where microphones continuously monitor the standing wave conditions in the cabin and feed this information back to the digital signal processing unit. The DSP analyzes the detected standing waves and adjusts the anti-phase signals accordingly, creating a closed-loop control system. This feedback mechanism enables the system to automatically adapt to changing vibration conditions, frequency shifts, and cabin acoustic changes over time, maintaining effective standing wave attenuation without requiring manual reconfiguration or long fixed-length pipes designed for specific initial conditions.
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 device achieves significant noise reduction and prevents howling, maintaining audio quality while adapting to varying frequencies and vibration conditions, demonstrating a high attenuation effect with minimal space requirements.
Implementation Method 1
an acoustic vibration input device which converts sound, including a standing wave component picked up by a microphone, into a sound signal
Implementation Method 2
an acoustic vibration output device which provides an output signal based on the processing result of the feedback comb filter
Implementation Method 3
a feedback comb filter which processes the sound signal to pass the standing wave component therethrough
Data Source
AI summary
A standing wave attenuation device is installed in a cabin of a vehicle so as to reduce a standing wave caused by external noise such as road noise. The standing wave attenuation device provides a closed loop including a feedback comb filter with a feedback loop, a microphone, a speaker, and a delay element. The delay element adjusts the phase of the output signal of the feedback comb filter such that the time needed for one-time circulation of a signal through the feedback loop matches a half period of the standing wave. An original sound including the standing wave is picked up by the microphone and subjected to processing so that the speaker produces a sound wave with the inverse phase against the phase of a sound wave constituting the standing wave, so that the standing wave is canceled out by the sound wave emitted from the speaker.