Abstract: When a high-speed train enters a tunnel, a compression wave is generated in front of the train, and then propagates towards the opposite portal with an approximate acoustic velocity. At the opposite portal, this wave is partly emitted from the tunnel portal in the form of pressure oscillation and induces a sonic boom. This is called a micro-pressure wave, and it causes some environmental problems. Based on tests of the ICE3 train, this paper sums up the characteristics of compression waves induced by the ICE3 entering tunnels with different portal shapes and the influence on the propagation of the compression wave by the presence or lack of an acoustic panel, as well as the effects of an acoustic panel and differently shaped portals on the mitigation of the micro-pressure wave. Furthermore, it introduces acoustic evaluation methods and results of the micro-pressure wave tests in Germany.