Loudness asymmetries for tones with increasing and decreasing levels using continuous and global ratings
Résumé
Loudness change has been studied for tones with linearly varying levels using different loudness rating methods, such as direct estimation or indirect estimation based on the starting and ending levels. The published results reveal an asymmetry depending on the direction of change (increasing vs. decreasing), the range of levels (high vs. low), and on the loudness rating method involved. The present study examines loudness asymmetry between increasing and decreasing levels for 1-kHz tones over the range 60-80 dB SPL and over four ramp durations (2, 5, 10 and 20 s) using two additional loudness ratings: continuous ratings and global ratings. A continuous analogical/categorical (A/C) rating scale was used, which consisted of an analog scale subdivided into seven discrete categories labeled from very, very loud to very, very soft. Two measures are obtained, examined and analyzed separately: indirect and direct loudness measures that correspond to the loudness change extracted from continuous ratings and the overall loudness impression, respectively. Loudness changes do not reveal any significant perceptual asymmetry between an increasing and a decreasing ramp. In addition, results do not reveal any "decruitment" effect, i.e. the loudness of a continuously decreasing tone changes more rapidly as a function of sound pressure level, which is in agreement with previous results for this range of levels. On the other hand, direct estimation of the global loudness, i.e. an overall loudness rating of the stimulus, is higher for an increasing ramp than for a decreasing ramp. This result is in agreement with previous studies and can be described by a memory process dominated by the ending level.