This paper provides a basis for discussion of the perception and use of graphic scales in modern listening tests. According to the literature, the distances between the adjacent verbal descriptors used in typical graphic scales are often perceptually unequal. This implies that the scales are perceptually non-linear and the ITU-R Quality Scale is shown to be particularly non-linear in this respect. In order to quantify the degree of violation of linearity in listening tests, the evaluative use of graphic scales was studied in three listening tests. Contrary to expectation, the results showed that the listeners use the scales almost linearly. This may indicate that the listeners ignore the meaning of the descriptors and use the scales without reference to the labels.
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