RV Repair: Silence engine noisy, coachman rv, sound deadening material

Question
I have a 1986 Coachman RV and the engine is very noisy so much so that the driver and passenger have a difficult time talking.  Someone tried to spray the inside of the doghouse cover with urethane foam but this hasn't done much.  Is there something we can use that will really work to silence the engine.  There is carpet over the outside of the doghouse.  Please any help will be much appreciated!  Thank you for your time and advise!
Thank you,
Lynda

Answer
i have a question for you.
has the carpet been replaced if so there is a sound Deadening material that goes under the carpet to help for the sound.
you can also add it the underside with some spray glue.
you can buy it at an autozone or advance auto