In this blog post, we will look at how noise affects the daily lives of modern people and whether noise cancellation is always the best solution.
In modern society, noise has become the enemy of people. The noise generated by all kinds of machines in the forest of buildings significantly reduces people’s concentration, and noise-induced hearing loss is now a common disease. In fact, many urban residents are suffering from serious noise pollution. Therefore, various efforts are being made to reduce noise, such as installing soundproof walls throughout the city and strengthening noise regulations. But is it really the best way to eliminate noise from machines?
It is no exaggeration to say that almost no household today does not use a refrigerator. The electric refrigerators we use today were developed in the 1920s by General Electric, founded by the famous Thomas Edison, and General Motors, which is currently leading the automotive market. However, early electric refrigerators were not only huge, but also had too much vibration and noise due to a lack of technology, so they could not be installed indoors like they are today. Later, technology developed, and the size was reduced to what it is today. Although the size has been reduced, the performance has improved, and the noise has been significantly reduced, so there is no sense of discomfort when installed indoors. In addition, research is steadily being conducted to develop completely noise-free refrigerators. However, the noise engineering community explains that completely eliminating noise is not as good an idea as it seems.
Noise engineering is the study of measuring “unpleasant sounds,” analyzing how they affect people, and researching ways to predict or suppress the generation of noise. Noise engineering divides noise into two broad categories. The first is aerodynamic noise, which is caused by the waves generated when an object collides with the air, and the second is structural noise, which is caused by the mechanical vibration of the adjacent air. The noise we feel is generally a combination of these two, and the unpleasantness of the noise is determined by the intensity and frequency of the sound. If the noise level is not high, it can be solved by using a noise-proof cover. However, when the size reaches the size of a car engine, it becomes difficult to prevent noise, and in fact, the vibration between the engine and the cover can cause even more noise. Therefore, the best way to reduce noise is to adjust the frequency. When a waveform formed by one frequency meets a waveform with an opposite phase, they cancel each other out. This principle is used to reduce noise, which is called active noise control. This method can theoretically eliminate noise completely. However, in reality, it is difficult to accurately identify the noise waveforms created by multiple noise sources at different locations at the same time. Since different designs are required for each noise waveform, current technology cannot eliminate all noise.
Noise engineering also initially focused on completely suppressing noise. However, faced with the difficulties described above, the research was shifted to improving the sound quality of noise rather than eliminating it. This change in direction was largely influenced by experiments on the relationship between noise and human psychology.
Most machines now generate noise, which is both a source of discomfort for people and a measure of machine performance. For example, if the noise of a vacuum cleaner is completely eliminated, people will be more interested in the vacuum cleaner because it can clean in silence, but they tend to feel that a vacuum cleaner that makes some noise performs better. A typical example is the sound of a car engine. Supercar manufacturers, that is, manufacturers of cars boasting the highest performance, pay special attention to the sound of their engines. They develop their own engine sounds every day and the sounds they develop are all patented. Maserati, one of the leading supercar manufacturers in Italy, is so focused on sound that it invites a symphony conductor to work on engine research. According to Wired, an American magazine that studies the impact of technology on society, people become excited when they hear the sound of a supercar engine, and the figure is higher for women in particular. This supports the claim that people perceive the sound of the engine as a measure of performance.
As we have seen, noise is a major problem in modern society. However, research in noise engineering has shown that eliminating noise is not the only solution. Of course, some people prefer the quietness of a luxury sedan, while others prefer the roaring engine of a supercar. Advances in noise engineering have made it possible to design for a variety of noise requirements. If the same car engine can produce different sounds, the scope can be expanded to the entire machine. Today, machines are used in a wide range of applications, from automobiles to construction and home appliances, and the types of machines are also diverse. There will be endless possibilities for what noise engineering can do in the future.
