Sound absorbing pipe lining having packing with different densities

Claim 1

IN A SOUND ABSORPTION DEVICE FOR DAMPING THE FULL SPECTRUM OF FRQUENCIES IN SOUND BEARING GAS PIPES, APPARATUS COMPRISING: A HETEROGENEOUS PACKING FORMED OF A SERIES OF POROUS SOUND OBSORBING MATERIALS CONSISTING OF TWO GROUPS WITH TWO DIFFERENT RESISTANCES TO FLOW DIRECTLY ADJOINING EACH OTHER IN ALTERNATELY ARRANGED SIDE-BY-SIDE RELATION WITH THEIR CONTACT SURFACES EXTENDING NORMAL TO THE FLUID FLOW DIRECTION THROUGH THE SOUND ABSORPTION DEVICE, SAID PACKINGS BEING ALTERNATELY OF GREATER AND LESSER DENSITY SO AS TO BE RESPONSIVE TO, AND ABSORB, THE FULL GAMUT OF FREQUENCIES PASSING THROUGH SAID DEVICE, SAID GREATER DENSITY PACKINGS OCCUPYING LESS VOLUME THAN SAID LESSER DENSITY PACKINGS, THE WIDTH OF EACH SAID GREATER DENSITY PACKING BEING AT LEAST FIVE TIMES THE WAVE LENGTH OF THE LOWER FREQUENCIES OF THE SOUNDS WHICH SAID GREATER DENSITY PACKING IS DESIGNED TO ATTENUATE.