Airborne Sound Sensing System Based on DAS and Ultra-Simple Transducer Structure

Abstract

Fiber-distributed optical fiber acoustic sensor (DAS) is generally used in distributed long-distance acoustic/vibration measurement. Recently, DAS is also used in weak airborne sound detection. To improve the sensitivity of DAS, using a state-of-the-art acoustic transducer or a special enhanced scattering fiber, which are uncommon in the industrial site, is often essential, according to the previous research. In this work, the fading of DAS is suppressed by the multi-frequency probes and polarization-diversity-receiver scheme. The self-noise of DAS is further lowered by the phase averaging of multiple acoustic channels wound on the transducer. We found that, supported by this high-performance DAS, even if the transducer is made with an ultra-simple plastic structure in daily life, the system can achieve high-sensitivity airborne sound sensing. The proposed simple acoustic transducer can reach the sensitivity level of −106.5 dB re. 1 rad/μPa at a sensing range of 5.1 km, which can meet many demands on the industrial site.

Keywords

• optical fiber
• distributed acoustic sensing
• phase-sensitive optical time domain reflectometry (OTDR)
• sound sensing