In this blog post, we will look at how car noise can be controlled and, furthermore, how unpleasant sounds can be turned into pleasant sounds.
When you walk along a road, you can’t help but frown at the noise made by the many cars. On roads with a lot of traffic, it’s even difficult to have a conversation with the person next to you. This noise is more than just an inconvenience; it also has a negative impact on psychological stress and health. Some studies have found that exposure to excessively high noise levels can cause not only hearing loss but also cardiovascular disease and sleep disorders. In particular, in large cities, persistent noise pollution has been pointed out as an important factor that reduces people’s quality of life. Therefore, noise issues are emerging as serious problems that should be addressed at the social and public health levels, beyond mere inconveniences in daily life.
Noise is still an important issue when you are in a car. The noise inside the car irritates the ears of the passengers, causing fatigue and making them nervous, which reduces their concentration while driving. In particular, such noise can increase the risk of accidents by promoting the accumulation of fatigue when driving for a long time. Therefore, controlling car noise is an important criterion for determining the comfort of a car. To reduce the damage caused by noise, society is also regulating noise emissions. Car manufacturers are researching and developing various methods for controlling noise and introducing technologies to provide consumers with a better driving environment. Let’s take a look at the ways we currently control car noise.
Imagine that loud music is playing in the corner of a room. Assuming that there are no obstacles between the speaker and you, all the loud sounds will come into your ears and make you suffer. How can you avoid this noise? First, you can surround the area around the speaker with thick walls. The thick walls act as a barrier between the speaker and me, making the loud music sound much quieter. Next, you can also eliminate the loud sound by generating another sound that can cancel it out. Sound is made up of waves with a cycle and shape. Therefore, sounds with the same cycle but opposite shapes, that is, opposite phases, are superimposed to cancel each other out. The last method is so simple that it is almost obvious, but it is to reduce the volume of the music that comes out of the speakers.
The same goes for the noise generated by a car. Car noise is generally generated by the engine running or by the friction between the tires and the road surface or between the car body and the air. If a car has no other devices besides the body, engine, and tires, the loud noise will come inside and interfere with driving. To block out these noises, the car body is surrounded by a wall made of sound-absorbing and sound-insulating materials. This wall absorbs, reflects, or blocks the noise generated by the car, making the noise much quieter. Automakers are constantly developing these technologies, and especially high-end cars use more sophisticated sound-absorbing and sound-insulating technologies to provide a quieter and more comfortable interior environment.
Next, there is an active noise control method that cancels out the noise inside the car. A microphone is installed in the car interior to directly measure the noise inside, and sounds of opposite phase are generated through the speaker to cancel out the noise. This is a technology that is especially useful in noisy large vehicles or electric vehicles. Finally, parts that generate noise are replaced with parts that generate less noise by changing the material or shape through research and development. In fact, the pattern on the tire is changed to another shape to reduce noise.
