Multiple layer fiber filled sound absorber and a method of manufacturing the same

A sound absorber comprising:

• an outer housing;
• an inner housing defining a passageway, a portion of said inner housing disposed within said outer housing and defining with said outer housing a first chamber adjacent to said inner housing and a second chamber adjacent said first chamber;
• a first sound absorbing material disposed in said first chamber;
• and
• a second sound absorbing material disposed in said second chamber, said first sound absorbing material being different from said second sound absorbing material, said sound absorbing materials being adapted to attenuate acoustic noise in a gas as it travels through said passageway, wherein said first sound absorbing material has a higher resistance to thermal degradation than said second sound absorbing material.

A sound absorber comprising:

• an outer housing;
• an inner housing defining a passageway, a portion of said inner housing disposed within said outer housing and defining with said outer housing a first chamber adjacent to said inner housing and a second chamber adjacent said first chamber;
• a first sound absorbing material disposed in said first chamber;
• and a second sound absorbing material disposed in said second chamber, said first sound absorbing material being different from sad second sound absorbing material, said sound absorbing materials being adapted to attenuate acoustic noise in a gas as it travels through said passageway, wherein said first sound absorbing material has a first density and said second sound absorbing material has a second density different from said first density.

A sound absorber comprising:

• an outer housing;
• an inner housing defining a passageway, a portion of said inner housing disposed within said outer housing and defining with said outer housing a first chamber adjacent to said inner housing and a second chamber adjacent said first chamber;
• a first sound absorbing material disposed in said first chamber, said first sound absorbing material including fibers having a first diameter;
• and
• a second sound absorbing material disposed in said second chamber, said second sound absorbing material including fibers having a second diameter, said second diameter being different from said first diameter, said sound absorbing materials being adapted to attenuate acoustic noise in a gas as it travels through said passageway.