The present invention relates to a device for passively reducing the noise vibrations in a liquid resulting from a sound source which is arranged below the liquid level of a body of water, the device comprising a noise-insulating pipe which is designed to be arranged around the sound source, wherein the pipe comprises a number of telescopically extendable and retractable pipe sections, fastening means for attaching at least one first and one second pipe section to one another in extended and/or retracted position, wherein the fastening means are designed to allow the mutual displacement of the pipe sections in a starting position and to attach the pipe sections to one another in a fastening position, and wherein the fastening means are also designed to keep the first and second pipe sections substantially acoustically disconnected in the fastening position.