Pure tone hearing threshold test The minimum sound intensity value of different frequency hearing was tested by pure tone audiometer, and pure tone hearing curve was drawn. 1.Conduction deafness: the bone conduction is normal or close to normal, and the air conduction hearing threshold is increased; there is a spacing between air and bone conduction, i.e. the air bone conduction gap (air bone gap) is generally not more than 60dB; the air conduction curve is flat, or the low frequency hearing loss is heavy so that the curve is rising. 2, conductive deafness (right ear) sensorineural deafness: air and bone conduction curve is consistent decline, no air bone conduction gap, generally high-frequency hearing loss is more severe, so the hearing curve is gradual decline or steep decline type. In severe sensorineural deafness, the curve is island-shaped. A small number of sensorineural deafness can also have predominantly low frequency hearing loss. 3.Sensory deafness (left ear) mixed deafness: both conductive deafness and sensorineural deafness have hearing curve characteristics. Both air and bone conduction curves are decreased, but there is a certain air-bone conduction difference.