Is the Hearing Threshold of Blind different from Normal Sighted Subjects

It is a common observation that when one sensory modality is lost or compromised other modalities improve in compensation as is true for tactile sensibilities of the blind persons which they use in their day to day activity. Hearing threshold of 25 male blind persons was assessed with aims to investigate whether hearing threshold of blind subjects was better than that of normal sighted subjectsby pure tone audiometry and was compared with that of 20 normal sighted subjects. The mean hearing threshold at frequency 250, 500, 1000, 2000, 4000 and 8000 Hertz was 16.5, 22.2, 17.4, 9.8, 13.8 and 16.3 in blind subjects and 15.13, 20.5, 16.13, 9.0, 10.25 and 12.0 in normal sighted subjects. Statistical analysis done by 't'-test showed no significant difference in the mean values of hearing threshold of the two groups. Although statistically there was no significant difference in the hearing threshold of the blind and the sighted, there is an increase in the hearing threshold of the both the groups. The cause could be rising levels of noise over the years. The loudness analysis is the function of the cochlea, thus this study tested the cochlear functions, which was not significantly different in the two groups. Individuals who become blind at an early life are better at localizing sounds than individuals with normal sight. Thus there could be significant difference in other auditory functions like discrimination of sound direction, pitch, tone, sequential sound patterns etc., which need to be studied