The International Young Physicists’ Tournament (IYPT) is a worldwide, annual competition for high school students. This paper is adapted from the author’s investigation into problem 4, Ball Sound , of the 27th IYPT. A novel set-up is proposed to investigate the unusual ‘chirping’ sound produced when two hard steel balls, or similar, are brought gently into contact with each other. It is shown that the decreasing time interval between rapid successive ball collisions, and not surface acceleration, is responsible for the chirping phenomenon. The proposed set-up simulates the collision of steel balls using our hands, and provides effective physical insights into the mechanism of chirp production.

中文翻译：

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研究chi声钢球：新颖的设置

国际青年物理学家锦标赛（IYPT）是一项针对高中生的全球性年度竞赛。本文改编自作者对第27届IYPT问题4“球形声音”的调查。提出了一种新颖的装置来研究两个硬钢球或类似的硬球轻轻接触时所产生的异常“ chi”声。结果表明，连续的快速球碰撞之间的时间间隔的减小而不是表面加速度的增加是造成the声现象的原因。拟议的设置可以用我们的双手模拟钢球的碰撞，并为effective的产生机理提供有效的物理见解。