The goal of this work was to evaluate the performance of the sound absorption for the recycled porous aluminum sheet instead of the traditional glass wool panel. A rectangular cavity had a wall to provide sound-pressure excitation, and its facing wall was covered with a porous aluminum sheet. The noise reduction effect was observed by the comparison of the sound between the cases with and without the cover. The impedance in the perpendicular direction to the surface in the experiment was employed as a boundary condition of the wave equation for numerical computation. The frequency characteristic and noise reduction characteristic for the two cases above was measured empirically. Both the calculation and the experiment showed the porous aluminum absorption sheet provided considerable noise reduction. Thus this material has many merits: It can be employed in a high-temperature environment, such as an automobile engine room, producing no pollution by dust as the case of glass wool; it makes it convenient to cover any surface due to its stiffness; and it is cheaper because it can be recycled. All of these applications ensure porous aluminum a promising future.