Measurements of vibrato parameters in long sustained crescendo notes as sung by ten sopranos

Two high-pitched and long sustained notes, F5 and A5, were selected from an aria found in ten commercial recordings of G Verdi's opera Aida by ten different sopranos. Both notes were sung without any instrumental accompaniment and with a crescendo. These audio examples were analyzed with regard to fundamental frequency, vibrato rate, vibrato extent, intonation and sound level, and the relationship among these parameters. The results reveal that vibrato rate differed significantly between the tones in most of the singers and confirm Prame's observations that vibrato rate tends to increase exponentially toward the end of tones. Moreover, both vibrato extent and mean F0 often varied systematically with sound level. The regularity of the vibrato tended to be greater at F5 than at A5.