There are often several issues to look at in order to get a good result. Noise picture may be different and often there is a lot of vibration. There is also a different level of ambition, such as working conditions on guard, when of guard and sleeping quarters for crew. Other cases are those where passengers will have a more comfortable walk in the lounges. The simplest cases are to reduce alarms from the machine.
Noise reduction is always best done as close as possible to the noise source. In medium to small engine compartments, one can dress as much as possible with ACOUSTIBLOK 3 mm canvas which must be glued onto bulkheads and ceilings, or attached in other sensible ways. This can be a problem if there are a lot of pipes, wires, fittings of different kinds and devices that are in the way. Then it is often the only solution to lay the Acoustic block on the floor over the machine room and dress with carpet, or a wear coating of some kind. If possible, it can also be something to be fetched if attached from motor to hull is protected by a vibration absorber like Sylomer.
Is there a larger engine room that is the workplace for the engineer, i.a. one can also see if there are shields or other surfaces on the machine can allow the gluing of the acoustic block to reduce the noise in the room. Here you can also consider other forms of direct absorbance on the bulkhead walls. See also Acoustiblok Marine.
Otherwise, the standard Acoustiblok is intended for homes, but the technical and part of the assembly can be transferred to ships. Acoustiblok is made by NASA in Florida and reduces about 80% (28-30 dB) of noise that would otherwise have gone through the surface you cover. This, of course, does not mean the experience afterwards, as a lot of noise is transported other roads.
Then to a series of products from PYROTEC. PYROTEK in the United States has a factory in Europe that has a wide range of special products for noise reduction in ships.