What it does
The project improves classroom acoustic quality by using 3D-printed metamaterial resonators that absorb and block unwanted noise especially in the speech frequency range of 500 to 4000 Hz, with a focus around 1000 Hz.
Your inspiration
The inspiration stemmed from the recognition that many Malaysian classrooms, especially those near busy roads, exceed the World Health Organization's recommended background noise level of 35 dBA. Traditional materials often fail to address this issue effectively or economically. The idea came from exploring the potential of acoustic metamaterials, which offer unique sound manipulation capabilities not possible with conventional materials.
How it works
The design utilises Helmholtz resonators, micro-perforated panels, and multi-chamber structures fabricated using Fused Deposition Modeling (FDM) with PLA material. These structures work on the principle of resonant sound absorption: when sound enters the cavity, it gets trapped and dissipated, particularly at specific frequencies. Impedance tube testing was used to measure sound absorption coefficients and transmission loss to evaluate performance. Two standout designs (E and G) were identified. Design E excelled at mid-frequency sound absorption, while Design G effectively reduced sound transmission.
Design process
Problem Identification: Studied acoustic data from Malaysian classrooms to identify 1000 Hz as a major noise issue. Resonator Type Selection: Compared four types (membrane, Helmholtz, local resonant, space-coiled) based on functionality, cost and manufacturability — Helmholtz was chosen. CAD Modelling: Created multiple designs in SolidWorks. Fabrication: Printed prototypes using PLA and Ultimaker Cura 3D printer. Testing: Evaluated using impedance tube, following ASTM standards, to measure absorption and transmission properties. Optimisation: Selected best-performing designs (E and G) for integration.
How it is different
This design stands out from traditional acoustic panels in several key ways: It specifically targets problematic speech frequencies (like 1000 Hz) based on real classroom noise data. It uses acoustic metamaterials engineered to exhibit sound-controlling properties not found in conventional materials. It is 3D-printed using PLA, making it lightweight, biodegradable, and cost-effective to produce. Unlike most products that only absorb or block sound, this design combines high absorption (Design E) and strong transmission loss (Design G) into a hybrid solution. The modular approach allows for customizable arrangements on classroom walls or ceilings to optimise performance.
Future plans
Field testing in real classroom environments to validate lab results. Optimisation of the design for mass production, possibly exploring modular panel systems. Integration with existing classroom infrastructure, such as ceilings or walls.
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