Language
Country/Area
No result found
Why is low-frequency noise easier to eliminate? Scientists reveal surprising truth!
Noise is everywhere in our daily lives. Whether we're walking down a busy city street or in a bustling office, we're often distracted by the sounds of the outside world. However, scientists have found that low-frequency noise is easier to cancel than high-frequency noise. The principle behind this has sparked a lot of research and discussion. The following will explore this phenomenon and its implications in depth.
What is Active Noise Control?
Active Noise Control (ANC) is a method of reducing noise. It does this by adding a specially designed sound to cancel out the original noise. The concept dates back to the 1930s, followed by further research in the 1950s and finally commercialization in the late 1980s. ANC technology is now used in a variety of devices such as headphones, cars, and mobile phones.
Sound is a pressure wave consisting of alternating compressions and rarefactions. The noise control speaker emits a sound wave with the same amplitude as the original sound but inverted phase. When the two meet, a new wave is formed, thus achieving the effect of noise cancellation.
Characteristics of low-frequency noise
Low-frequency noise has a longer wavelength, so fewer detectors are needed compared to sound waves distributed in the air. Therefore, it becomes easier to handle this type of noise in one or three dimensions. At the same time, low-frequency noises tend to be repetitive, which means their waveforms have a periodic nature, making it easier to cancel the noise.
The challenge of high-frequency noise
In contrast, high-frequency noise becomes more difficult to control in three dimensions due to its short wavelength. When these sounds come from different directions, they may be strengthened in some locations and weakened in others, resulting in a rather uneven effect. Especially when the listener moves or turns his head, the interference range of high-frequency noise will be more complicated.
For high-frequency sound waves, interference in three-dimensional space becomes even more unpredictable. This means that in some ears the sound may be perceived as enhanced, while in other ears it may be the opposite.
Technology application and development history
Active noise control is showing its potential in applications ranging from noise-canceling headphones to car cabins. This technology has undergone several important developments over the past hundred years. In 1936, Paul Luger patented a noise control system. Then in the 1950s, more researchers began to explore how to apply these technologies in the cockpits of aircraft and helicopters.
The theory of mixed noise in the 1940s made people gradually realize the controllability of sound, making the realization of noise filtering feasible.
The difference between active and passive noise control
In noise control, active noise control relies on electrical sources for sound reduction, while passive noise control uses sound-deadening materials such as insulation or mufflers to mitigate the propagation of sound waves. Active noise control is better suited for reducing low frequency noise, but passive control becomes increasingly powerful as the frequency increases, and can often solve the problem without the need for active control.
More possible future directions
With the advancement of science and technology, the potential of noise control technology in the future is undoubtedly huge. Some experts are working on more advanced algorithms to more effectively handle the challenges of noise in three-dimensional space. In addition, the combination of active and passive technologies may open up new methods of noise control.
In life, does noise affect our physical and mental health? Such questions may often trigger our thinking and attention to noise issues?
