Contribution
Reliable Measurement Equipment for Airborne Infrasound
* Presenting author
Abstract:
The demand for reliable assessment of airborne infrasound has increased, with applications for example in global monitoring or in legal metrology. In recent years, several calibration facilities have been established, which provide traceability to the SI for infrasound measurements. Furthermore, measurement equipment intended for the assessment of infrasound is commercially available. However, the available measurement equipment does not fully cover the requirements for reliable infrasound assessment. Conventional microphones and preamplifiers are limited to the audible frequency range. While both can be adapted for low-frequency use, they still show inherent high pass behavior. Conventional sound calibrators for periodic testing are mainly limited to frequencies of 250 Hz or 1000 Hz. This contribution covers developments in measurement equipment especially designed for the assessment of infrasound. Based on a conventional measurement microphone, a microphone with a lower frequency cutoff is designed. To prevent the introduction of additional high pass behavior by the preamplifier, multiple alternative working principles for microphone preamplifiers were investigated. Finally, initial investigations were conducted into the realization of portable infrasound calibrators utilizing the comparison method. These developments are a valuable contribution to the availability of reliable measurement equipment for airborne infrasound.