A long-term study of auditory disturbance of a female case who had suffered from pure word deafness associated with Landau-Kleffner syndrome was reported. The patient developed this syndrome at age 4, and we continued the follow-up until she reached 20. The following became clear after the investigation: (1) even by the age of 20 her auditory defect had not improved significantly; (2) from an early stage she could not identify either vowels or consonant-vowel syllables; (3) later she had no difficulty identifying vowels, but her consonant-discrimination score hardly improved; and (4) her problem in consonant identification was unique in that she could discriminate between the voiced and voiceless group but had great difficulty identifying the consonants within each group. These findings led to the conclusion that the patient is unable to recognize short time duration consonants due to an insensibility to loudness and a defect in temporal resolution.