Sound transmission loss control using electrorheological fluids

In the modern noise-polluted world, there exists an increasing demand for better noise protection. In search for better quality of that protection, new noise damping techniques and materials are being developed. This work was done in order to find out whether electrorheological (ER) fluids could possibly be applied in the noise control. The sound transmission loss (STL) parameter was investigated for three different kinds of ER suspensions in the sound frequency range between 100 and 2000 [Hz]. Of particular interest was the influence of an electric field density on STL of ER fluids in various electrode configurations. It has been found that with the increase of the electric field the sound transmission loss of ER suspensions decreased, especially in the low frequency range (100--300 [Hz]). The STL drop-electric field density dependence can be well described by the quadratic type of equation. Results indicate that ER fluids offer a good STL control authority---this effect can be applied in active noise control devices. Some further investigations were also recommended.