Abstract
Noise barriers are often very tall alongside highways with heavy traffic. Although these high barriers ensure the desired amount of noise attenuation, they are expensive to install and have a negative effect on the landscape. Consequently, many types of edge-modified noise barriers have been proposed to reduce the necessary height. Herein an alternative noise barrier based on the ``edge-effect'' suppression technique is proposed, and the sound insulation performance is investigated both theoretically and experimentally. Numerical examples indicate that the diffracted sound is greatly attenuated by suppressing the particle velocity in the region with a large velocity amplitude using a thin absorbing material such as cloth with a gradational distribution in impedance. The experimental and theoretical results of insertion loss are in good agreement, validating the theoretical consideration and effectiveness of the cloth installed at the top of the barrier.
