Experimental　and　numerical　studies　were　conducted　to　investigate　passive　control　of　a　forward-curved　centrifugal　fan　noise　by　employing　the　open-cell　metal　foam　(OCMF).　The　results　indicated　that　a　reduction　of　about　5　dB　in　overall　A-weighted　sound　pressure　level　(OASPL)　was　successfully　achieved　with　a　decline　of　about　200　Pa　in　total　pressure　rise　(TPR).　For　the　OCMF　investigated　in　the　present　paper　with　the　pores　per　inch　(PPI)　of　20　and　the　porosity　of　97%,　the　noise　control　mechanism　was　to　suppress　the　source　strength　of　tonal　noise　generated　from　the　periodic　impeller-tongue　interaction　rather　than　to　absorb　the　broadband　acoustic　energy.　The　decline　of　the　aerodynamic　performance　was　mainly　caused　by　reducing　the　work　capacity　of　the　impeller　rather　than　caused　by　flow　loss　owing　to　the　flow　resistance　of　the　OCMF.　An　improved　design　of　the　OCMF　was　suggested　to　achieve　more　reduction　in　noise　level　with　less　decline　of　aerodynamic　performance.　(C)　2015　Elsevier　Ltd.　All　rights　reserved.