Ordinal scaling of temporal audio descriptors and perceptual significance of attack temporal centroid in timbre spaces

Temporal audio features play an important role in timbre perception and sound identification. An experiment was conducted to test whether listeners are able to rank order synthesized stimuli over a wide range of feature values restricted within the range of instrument sounds. The following audio descriptors were tested: attack and decay time, temporal centroid with fixed attack and decay time, and inharmonicity. The results indicate that these descriptors are susceptible to ordinal scaling. The spectral envelope played an important role when ordering stimuli with various inharmonicity levels, whereas the shape of the amplitude envelope was an important parameter when ordering stimuli with different attack and decay times. Linear amplitude envelopes made the ordering of attack times easier and caused the least amount of confusion among listeners, whereas exponential envelopes were more effective when ordering decay times. Although there were many confusions in ordering short attack and decay times, listeners performed well in ordering temporal centroids even at very short attack and decay times. A meta-analysis of six timbre spaces was therefore conducted to test the explanatory power of attack time versus the attack temporal centroid along a perceptual dimension. The results indicate that attack temporal centroid has greater overall explanatory power than attack time itself.