Study on Relationship between Subjective Reproducibility of Individuality for Vibrato of Singing Voice and Vibrato-feature Distortion Reflecting Magnitude of Fluctuation of Fundamental Frequency

Abstract

In our previous study, a distance measure between two vibratos had been developed to evaluate singing style. This paper verifies whether the measure properly represents subjective distance by the following two subjective experiments. In these experiments, synthetic sounds whose vibratory amplitude computed from a target singer's singing is variable were used, and listeners were asked to answer reproducibility of individuality of the target singer for the synthetic sound. In the first experiment, listeners were asked to remember vibrato of the target singer by listening to the singing before the experiment. As a result, it was found that not only synthetic sounds showing small distance to the target singer in the distance measure but also those not showing small distance produced high subjective reproducibility, and the reproducibility score of the latter sounds is up to 1.2 times as higher as that of the former sounds, as long as the latter sounds have large vibratory amplitude, in other words, the sounds are just like the performance with deformation. To confirm whether this tendency is caused by the experimental procedure, the second experiment that listeners were asked to compare the synthetic sound with the reference singing sound of the target singer was conducted. This experiment also showed that subjective reproducibility of the synthetic sounds with large vibratory amplitude is higher than or almost equal to that of the reference singing sounds.