Top 2 Noise Reduction Technologies – Interesting Innovations that cancel noise!

noise reduction technologies

Interesting Noise Reduction Technologies

How often have you been disturbed by the noise of the passing vehicle especially when you are on an urgent call or attending an important conference? Well, we all hate noise even when we are not involved in any activity let alone working. Urban noise pollution is becoming an increasingly serious problem in today’s world.

Due to the non-availability of any dedicated solution for reducing noise especially for homes, offices, or public spaces, we have to bear with the discomforting decibels.

Fortunately, you might soon be able to beat noise that interferes with your comfort. Two of the world-renowned universities have developed noise reduction technologies that can cancel noise coming from a loud source.

Let’s have a look at each of them.

An Acoustic Metamaterial

A team of Researchers (Reza Ghaffarivardavagh, Stephan Anderson, Xin Zhang, and Jacob Nikolajczyk) from Boston University have come up with a solution that is capable of blocking 94% of sound while allowing light and air to pass through it. The innovation is a combination of math and 3D printing that resulted in such a wonder.

A ring has been 3D printed from a mathematically modeled design. Its shape allows it to catch certain frequencies passing through the air and reflect them toward their source.

Among the other noise reduction technologies that are available, this one is quite versatile in the sense that its structure is super lightweight and each piece could be used as a tile or brick to scale up and build a sound-canceling permeable wall as well.

A typical acoustic panel absorbs sound which turns into heat. These panels are tightly packed to block sound. But this “acoustic meta-material” is completely different because it’s open and allows air and light to pass through it but not sound. This aspect of the technology makes it revolutionary and suitable for a wide range of applications.

The Experiment
The 3-D printed material was attached to one end of a PVC pipe, the other end of which was attached to a loudspeaker. When a high-pitched note was blasted from the loudspeaker, it was found that the shape blocked 94 percent of the sound coming through the pipe.

Mechanical Engineers at Boston University with the acoustic meta-material

The Applications
The most interesting part of this noise reduction technology is its applications. It finds its uses in several areas.

  1. In HVAC, this device can reduce the noise coming from various components especially compressors. Since it is a single material based device, it makes it more reliable and easy to install.
  2. In drones, this device can be placed beneath the drone fans which can cancel out the sound radiating towards the ground.
  3. In MRI machines, the material can be made to fit inside the central bore of an MRI and shield the patients from the sound generated.
  4. During the present pandemic, most of the people are working from their homes. But they struggle with the noise and disturbance that comes from different sources like pets, children, running vehicles, etc. This innovation can be scaled and fixed on the doors or windows of the room to cancel out noise.
  5. Through further research, the device can be evolved to cancel out the noise coming from the engines of aircraft.
  6. A sound-canceling breathable wall that can enable multi-conferences to happen simultaneously inside the same hall – An application that enables resource utilization for real estate companies with unutilized spaces.

Using an approach to uncover profitable markets, several other rewarding applications of this promising technology can be uncovered.

Noise-Cancelling Smart Window

Researchers at Nanyang Technological University have developed a technology that cancels out noise entering the rooms through windows using an array of small speakers.  

A sensor picks up a regularly repeating waveform, like the sound created by a rolling wheel or a turning propeller. Electronics characterizes the wave, generates a mirror image of it, and emits that second “anti wave” from a speaker, causing the two waves’ peaks and troughs to cancel out.

Antinoise (as in headphones) works best for frequencies between300 Hertz & 1000 Hz and in limited spaces, where the wave and its anti wave are sure to exactly meet up and match, as in the gap between a headphone and an ear.  But the unique thing about this noise reduction technology is the perfect matching of the wave and anti wave throughout the entire room. The key is that all the noise comes through a relatively small aperture. The aperture in this case is a window that is treated as a noise source.

NTU Singapore: A glass pane with a sensor (left) that detects street noise & an array of speakers (right) emits the corresponding antinoise signal.

The Experiment
An array of 24 small speakers are placed in a window, together with a sensor and made to generate an antinoise signal to cut the room’s noise. It is observed that the room’s noise is cut by 10 decibels as perceived by the human ear.

The Applications
The applications are more or less the same as for the acoustic meta-material described above with the only limitation that the present state of this noise reduction technology cannot be used in open spaces where the noise source is far away for example an aircraft.

To Wrap Up

Noise is an undesirable by-product which needs to be mitigated. The available noise reduction technologies have failed to get rid of it due to their limitations. However, the recent advancements or breakthroughs have instilled a promise to beat this discomforting evil. The noise reduction technologies described above are a major step towards achieving this.

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