The pure tone audiometry, SISI test, tone decay test, speech reception threshold and speech discrimination score were carried out for 100 ears of hearing loss of various causes, i.e. 26 cases of conductive hearing loss, 29 cases of mixed hearing loss and 45 cases of sensori-neural hearing loss. The results were as follows ; 1) The mean value of speech reception threshold and speech discrimination score in conductive hearing loss, mixed hearing loss and sensori-hearing loss showed nearly same value. 2) The lowest value of speech discrimination score was observed in sensorineural hearing loss, 76.1% and 87.5% in mixed hearing loss and 89.7% in conductive hearing loss. 3) The dynamic range of conductive hearing loss was 27.3 dB and 4.2 dB in sensorineural hearing loss and 3.4 dB in mixed hearing loss. 4) The positive SISI score at 1,000 Hz was 3.8% in conductive hearing loss 0% in mixed hearing loss and 11.1% in sensorineural hearing loss. The positive SISI score was observed more frequently in sensorineural hearing loss than other types at 500 Hz, 2,000 Hz and 4,000 Hz. 5) The amount of tone decay was more larger in sersorineural hearing loss than other types.