Acoustic Field Distortions Caused by Helium-Filled Balloons

In this paper, an automated measurement system was proposed that uses a probe hung below a remotely controlled balloon to measure parameters of the acoustic eld in the whole volume of a room. The study was conducted to estimate distortions that such system may cause in the acoustic eld at the measurement point. The most signi cant source of the distortions will be the buoyancy element one large balloon or a number of smaller ones. This paper considers di erent spatial con gurations of spherical balloons with regards to alterations they cause in the acoustic pressure levels measured below them. Interior of a room without and with a group of spherical balloons was modeled using the boundary element method. Using a larger number of smaller spheres instead of a single large one did not signi cantly reduce the related distortions. However, using two spheres slightly decreased distortions when the distance between the balloons and the recording point was relatively small.