| Résumé |
Four experiments were conducted to assess the loudness of both increasing and decreasing intensity sounds using different methods and context of presentation as between-subjects factors. In Exp1 and Exp 2, loudness was assessed directly by using magnitude estimation procedures, with increasing and decreasing sounds presented respectively either in the same block or in separate blocks. In the other two experiments, loudness was measured by the mean of pairwise comparisons. While increasing and decreasing sounds were compared with each other in Exp 3, they were compared respectively with constant-intensity sounds in Exp 4. Two-intervals, 2AFC interleaved-adaptive procedures were used to prevent from potential biases. As a result, very similar trends were observed in the four experiments. In particular, the loudness difference between increasing and decreasing sounds always felt within the same range: decreasing intensity sounds need to be about 3 dB louder that increasing sounds to be perceived with equal loudness. This study thus indicates that this loudness asymmetry actually corresponds to a true perceptual effect and is not due to any experimental bias, since a clear consistency across the results was found using different measurement methods and context of presentation. |
