Loudness Perception of the Blind

Abstract

Over the years numerous stories have evolved about the perceptual abilities of the blind. This study was an attempt to examine one area of auditory function of blind subjects - that described by equal-loudness contours. The hypothesis under test stated that there is no significant difference between the blind and sighted in thewir perception of loudness as described by equal-loudness contours.

To test the experimental hypoothesis, equal-loudness contours were constructed from the results of loudness judgements by 20 blind and 20 sighted subjects. The stimuli were presented under binaural earphone conditions. A method of constant stimuli was employed whereby each subject made judgements of louder or softer to comparison stimuli presented sequentially with fixed intensities of a 1 000-Hz reference tone.

The results indicated that very little difference between the data for the blind and sighted subjects for the overall equal-loudness contrours or within any single frequency or across any of the phon contorus. Therefore, the null hypothesis that stated that there is no significant difference between the blind and sighted in their perception of loudness as described by equal-loudness contours was not rejected. Based on these results, it appears doubtful that any physiological difference in loudness perception exists between the blind and sighted.

Key Words:

• Equal-loudness contours
• Method of constant stimuli