A review of the condition assessment methods of porcelain insulators shows that there is motivation for further improvements particularly regarding applications in distribution systems. Acoustic and high frequency (HF) methods are quite attractive mainly due to better immunity to noise and the relative easiness with which they can be adapted to in-service monitoring applications. These methods have therefore attracted considerable attention in recent research work. A laboratory experiment was set up to study electrical discharges on artificial defects made on porcelain insulators. A standard partial discharge detection method was used simultaneously with acoustic and high frequency techniques. Comparisons and contrasts of the signals were done. All the techniques gave discharge signals that had distinct features for each defect. This opens up opportunities for defect recognition through discharge signal processing.