A portable infrasound source based on a pneumatic siren design is described. The source is capable of producing narrowband tone bursts over a frequency range of approximately 0.25–10 Hz. The acoustical characteristics of the infrasound source are presented, including measured sound pressure levels and horizontal directivity. The methodologies for processing the received acoustic signals are reported, and comparisons of measurements are made with a simple multipole model of the source. Measurements indicate that the pneumatic infrasound siren can be useful for a variety of applications for which a controlled, known infrasound source is required.

中文翻译：

---

便携式气动次声源的声学特性

描述了一种基于气动警报器设计的便携式次声源。该信号源能够在大约0.25–10 Hz的频率范围内产生窄带音频突发。介绍了次声源的声学特性，包括测得的声压级和水平方向性。报告了用于处理接收到的声信号的方法，并使用源的简单多极模型进行了测量比较。测量表明，气动次声警报器可用于需要受控，已知次声源的多种应用。