What is the problem? Ventilation ducts are needed to dissipate heat and supply cool air. However, these channels regularly compose sound leakages as well, since they constitute open connections between the outside environment and the engine room.
What is the solution? The solution for round ducts is the simplest for round ducts. After removing all plugs, place at least two Inno Dampers with a mutual space of about 10 cm. The solution for ducts that have a rectangular shape is to cover the inside with an absorption material, such as Tecnocell in dry ducts and Acusticab in ducts where the material could become damp.
If don't have access into the canal, you add a so-called labyrinth to the canal. This is best described as a tunnel containing walls equipped with an absorption material. In this way, the air has to go through a number of curves that absorb the sound as much as possible.
Below you will find the described products to insulate the air ducts