Helmholtz’s clue: Russian physicists have developed technology to reduce noise
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Noise-canceling “bagels” will appear in parks
A noise-suppressing protective system, which, however, allows air and light to pass through, was developed by ITMO University scientists. It consists of many tubes – Helmholtz resonators, passing through which the sound wave gradually fades away.
Noise can lead to hearing impairment, diseases of the cardiovascular and nervous systems. This problem is especially acute in big cities. Scientists have found a way to remedy the situation.
As MK was told at the university, a simple structure was developed here to suppress acoustic noise in the audible frequency range. It is based on coupled Helmholtz resonators, shaped like tubes with a side cut. The inventor used them to analyze acoustic signals, and modern engineers based them on a model of a soundproof gazebo for parks. The wall in the form of a round donut, protecting the communication space from the noisy zone, consists of 3D-printed plastic Helmholtz resonators.
As a result, due to several noise reduction mechanisms, it was possible to reduce the sound level for a wide range of frequencies. Scientists have verified this in the following way. A speaker was installed outside the donut, a microphone was placed inside the structure, and then the signal level was measured, first without the structure, and then with it. It turned out that the noise-reducing “fence” reduces the noise level by an average of 20 dB (about 10 times) in the range from 2 to 16.5 kHz.
The researchers’ next step will be a real prototype of the noise-isolating structure, which can be tested in an anechoic chamber. According to the developers, the total thickness of such a fence will be no more than 10 centimeters. In the future, this technology may be useful not only for gazebos in the park, but also for fencing along roads and railways.
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