Tunable Loudspeaker Absorber for Low-Frequency Noise
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Solution Overview
Problem
Existing electroacoustic absorbers lack tunability and effective sound absorption at low frequencies, particularly due to the challenges of prestress in membrane-type acoustic metamaterials, which complicates fabrication and reduces their performance in noisy environments.
Innovation Solution
A system comprising a loudspeaker, an absorber, and a control circuit that adjusts the acoustic impedance of the loudspeaker by tuning its resonance using a microphone to acquire sound data and a control circuit, allowing for real-time adjustment of sound absorption characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If membrane-type acoustic metamaterials are used for sound absorption, then sound absorption performance is improved, but fabrication complexity increases due to prestress requirements
Solution Approach 1:
The patent replaces the mechanical prestress system with an electrical control system. Instead of physically pre-stressing the membrane to achieve resonance, the system uses an actuator (such as a piezoelectric actuator or voice coil) to dynamically adjust the membrane tension through electrical signals. This substitution eliminates the complex fabrication processes required to apply and maintain mechanical prestress while enabling tunable resonance frequencies for effective low-frequency sound absorption.
Solution Approach 2:
The patent transforms the static membrane structure into a dynamic, adjustable system. The membrane tension and resonance frequency can be changed in real-time through electrical control, allowing the absorber to adapt to different sound frequencies. This dynamic capability is achieved by replacing fixed mechanical prestress with controllable electrical actuation, making the system both easier to manufacture and more versatile in performance.
2Device complexity
If fixed acoustic impedance is used in electroacoustic absorbers, then device simplicity is maintained, but tunability and adaptability are reduced
Solution Approach 1:
The patent introduces dynamic adjustability to the acoustic impedance through electrical control. The membrane tension, and consequently the resonance frequency and acoustic impedance, can be modified in real-time by adjusting the electrical signal to the actuator. This allows a single device to adapt to various sound absorption requirements without complicating the basic structure, maintaining simplicity while adding versatility.
Solution Approach 2:
The patent enables change in key acoustic parameters (resonance frequency, acoustic impedance) through electrical control of the membrane tension. By adjusting the electrical signal to the actuator, the system can tune these parameters to match different target frequencies, providing adaptability without requiring multiple fixed-impedance devices or complex mechanical adjustment mechanisms.
3Ease of operation
If passive acoustic absorbers are used, then ease of operation is maintained, but effectiveness in noisy environments with varying frequencies is reduced
Solution Approach 1:
The patent incorporates feedback control to enhance performance in varying noisy environments. A microphone or sensor detects the ambient sound frequency, and this information is fed back to the control circuit, which adjusts the actuator signal to tune the membrane resonance to the detected frequency. This automatic feedback mechanism maintains ease of operation (no manual adjustment needed) while significantly improving reliability in dynamic acoustic environments.
Solution Approach 2:
The patent transforms the static passive absorber into a dynamic active system that can adapt its resonance frequency in real-time. The membrane tension is continuously adjustable through electrical control, allowing the device to track and respond to changing sound frequencies in noisy environments. This dynamic capability maintains operational simplicity while dramatically improving effectiveness across varying acoustic 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 system enhances sound absorption performance by providing a tunable and efficient means to reduce noise levels, improving health, comfort, and productivity by effectively managing sound waves and their reflections.
Implementation Method 1
The control circuit can be configured to tune a resonance of the loudspeaker, thereby causing an acoustic impedance of the loudspeaker to be adjusted
Implementation Method 2
The absorber can be configured to absorb sound waves
Data Source
AI summary
A system can improve the performance of an electroacoustic absorber. The system includes a loudspeaker and an absorber operatively positioned relative to the loudspeaker. The absorber can be configured to absorb sound waves. A control circuit can be operatively connected to the loudspeaker. The control circuit can be configured to tune the resonance of the loudspeaker and therefore cause one or more acoustic characteristics, such as acoustic impedance, of the loudspeaker to be adjusted.