Timbre Vibrato Perception and Description

In music, vibrato consists of cyclic variations in pitch, loudness, or spectral envelope (hereafter, “timbre vibrato”—TV) or combinations of these. Here, stimuli with TV were compared with those having loudness vibrato (LV). In Experiment 1, participants chose from tones with different vibrato depth to match a reference vibrato tone. When matching to tones with the same vibrato type, 70% of the variance was explained by linear matching of depth. Less variance (40%) was explained when matching dissimilar vibrato types. Fluctuations in loudness were perceived as approximately the same depth as fluctuations in spectral envelope (i.e., about 1.3 times deeper than fluctuations in spectral centroid). In Experiment 2, participants matched a reference with test stimuli of varying depths and types. When the depths of the test and reference tones were similar, the same type was usually selected, over the range of vibrato depths. For very disparate depths, matches were made by type only about 50% of the time. The study revealed good, fairly linear sensitivity to vibrato depth regardless of vibrato type, but also some poorly understood findings between physical signal and perception of TV, suggesting that more research is needed in TV perception.