Tinnitus is one of the most common complaints in the practice of otolaryngology, and it is usually accompanied by otologic disease or systemic illness. In practice, normal hearing persons who have no otologic diseases can experience certain sounds in an anechoic room. Most of them, however, are not aware of their tinnitus, due to the masking effect of ambient noise. We attempted to evaluate the character of the tinnitus by exposing eighty-one normally hearing persons to an anechoic room in which the ambient noise level is considerably low. The results were as follows : 1) The incidence of tinnitus perception in an anechoic room was 88.89%. 2) Unilateral tinnitus was perceived in 45.83% of all cases and, bilaterality, in 54.16%. 3) 'U' and 'I' were predominant vowels in onomatopoeic word. 4) Pitch matching of tinnitus was consistent with the low and middle frequency, and 87.5% of all perceivable cases corresponded to pure tone. 5) 70.83% of tinnitus was masked by white nose at the level of 15dB.