A novel approach to reducing tire noise: Pitch sequence engineering

Tire noise is an important factor affecting the comfort of a car. Tire noise not only disturbs the mood of the driver and passengers, but also causes noise pollution to the surrounding environment. Therefore, reducing tire noise is a common concern of the automotive industry and consumers. This article will introduce a novel method to reduce tire noise - pitch sequence engineering. Tire noise mainly comes from the interaction between the tire and the road surface. Pitch sequence engineering is a technology that uses acoustic principles to control the frequency and intensity of the sound emitted by the tire by designing the shape and arrangement of the tire pattern.

The inspiration of pitch sequence engineering comes from singing synthesis technology. It can synthesize singing with different styles and expressiveness by adjusting parameters such as phonemes, pitch, and duration. The basic principle of pitch sequence engineering is to use the sensitivity and discrimination of the human ear to sound frequency. The human ear has a threshold for sound frequency. Sounds below or above this threshold are difficult for the human ear to hear or distinguish. This threshold changes with the sound intensity and the surrounding environmental noise, and is generally between 20Hz and 20kHz.

Based on these characteristics, we can design a tire pattern so that the sound frequency it emits is distributed within a range that is difficult for the human ear to detect or distinguish, thereby achieving the purpose of reducing tire noise. Specifically, there are several steps. First, analyze the frequency and intensity of the sound generated when the tire contacts the road surface to obtain a spectrum graph. Second, select a target frequency range so that the sound intensity within this range is lower than the human ear threshold or higher than the human ear resolution. Third, design a tire pattern shape and arrangement so that the sound frequency it emits is mainly concentrated in the target frequency range.

In the 1920s, car tires made squeaking noises, which were largely caused by the tread pattern. The tread pattern at the time was very simple, consisting of a number of blocks of similar size and shape. These blocks were arranged in a grid, and when the car was driving, they would regularly contact the ground, which caused them to vibrate at the same frequency. If we look at the frequency spectrum, there will be large peaks at certain frequencies.

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

On modern tires, the tread blocks are divided into groups of different lengths, with different patterns within each group, and the order of these groups on the tire is also random. It is this pattern that greatly reduces the peaks of the sound, making the tire sound more pleasant.