简介：TheapplicationofBEMtocalculateacousticradiationfromclosedsurfaceinaninfiniteacousticme-diumhastheadvantagesoflessmemoryspace,higheraccuracyandfastercalculatingspeed.However,thesingularintegralsandthenonuniquenessproblemofsurfacehelmholtzequationatcharacteristicfrequen-ciesshouldbedealtwith.ItissuggestedinthispaperthatcombinationoftheinteriorHelmholtzequationanditsderivativeswithrespecttothecoordinatecomponentsofaninteriorpointformsanextraequation,inordertosolvetheproblemsofacousticradiationatvariousfrequencieswithsurfaceHelmholtzequation;ontheareawhichincludessingularpoint,thesingularintegralsareconvertedtoordinaryonesbypolarcoordinatetransformation.Asanexample.theacousticradiationfieldofclosedaxisymmetricsurfaceswithprescribedsurfacevelocitydistributioniscalculatedinthispaper.