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Tire noise is an important factor affecting car comfort. Tire noise will not only interfere with the mood of drivers and passengers, but also cause noise pollution to the surrounding environment. Therefore, reducing tire noise is a common concern of both the automobile industry and consumers.

This paper will introduce a novel method to reduce tire noise-pitch sequence engineering. The noise of the tire mainly comes from the interaction between the tire and the road. Pitch sequence engineering is a technology that uses the acoustic principle to control the sound frequency and intensity of the tire by designing the shape and arrangement of tire patterns. Pitch sequence engineering is inspired by song synthesis technology, which can synthesize songs with different styles and expressiveness by adjusting phoneme, pitch, duration and other parameters.

The basic principle of pitch sequence engineering is to make use of the sensitivity and discrimination of human ear to sound frequency. The human ear has a threshold for the sound frequency, and it is difficult for the human ear to hear or distinguish the sound below or above this threshold. This threshold varies with sound intensity and ambient noise, generally between 20Hz and 20kHz.

According to these characteristics, we can design a tire pattern so that its sound frequency is distributed in a range that is not easy to be detected or distinguished by human ears, so as to achieve the purpose of reducing tire noise. Specifically, there are the following steps.

First of all, a frequency spectrum is obtained by analyzing the sound frequency and intensity produced when the tire is in contact with the road surface. Second, select a target frequency range so that the sound intensity in this range is lower than the human ear threshold or higher than the human ear resolution. Thirdly, a tire pattern shape and arrangement are designed so that the sound frequency is mainly concentrated in the target frequency range.

In the 1920s, car tires made a harsh noise, which was largely due to tread patterns. At that time, the tread pattern was very simple, made up of blocks of similar size and shape. These pattern blocks are arranged in a grid, and when the car is driving, they come into regular contact with the ground, which causes them to vibrate only at the same frequency. If we look at the spectrum, there will be large peaks on some frequencies.

To solve this problem and eliminate the noise, engineers want to spread out the sound energy, flatten the peak, and finally become similar to white noise. A 1935 patent began to solve this problem by staggering the tread patterns so that they would not hit the ground at the same time. In addition, it also changes the pattern into three different sizes and shapes: large, medium and small. We can see that the peak is smoother in the spectrum, but there are still three main peaks, because the distribution of the pattern blocks is not random enough.

On modern tires, the pattern blocks are divided into groups of different lengths, the patterns in each group are also different, and the order of these groups on the tire is random. It is this mode that greatly reduces the peak sound and makes the tires sound more pleasant.

This article comes from the official account of Wechat: Vientiane experience (ID:UR4351), author: Eugene Wang

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