'A good vibrato in music is a periodic pulsation, generally involving pitch, intensity, and timbre, which produces a pleasing flexibility, mellowness and richness of tone.'

Ebben van valami, magyarul, az éneklés nem vegytiszta, pontosabban fiztiszta FM vagy AM, hanem FM + AM + hangszín + ...

Carl Emil Seashore tanulmánya valóban nagyszerű, következésképpen abban nem fordul elő a vibrato rate kifejezés. És a szerző persze svéd. :-)

Vibrato by the Seashore
...He provided us the definition of vibrato that we still understand today: a periodic fluctuation of pitch, amplitude, and timbre...

Carl Emil Seashore
Seashore dedicated some of his musical focus on understanding the perception of vibrato, or the pulsation of pitch, in music and its effects on the richness and vibrance of tone. He spent considerable time to measure, record, and define the function of vibrato in music. He described vibrato as "a basic phenomenon of nature" to provide the tone with richness and emotion. Seashore proposed using devices and measuring instruments to record musical patterns and analyze the frequency, pulsation, and occurrence of vibrato in music.

Brigham Young has an extremely conservative "Honor Code" derived from the Mormon Church that requires, among other things, abstinence from drugs, alcohol, tobacco, coffee, and tea...
Master of Science résztanulmány. Látszik, hogy a szerző még kávét sem ivott, amíg mindezt összehozta. Az azért elég ritka, hogy már az első oldalon is díszeleg értelmetlen mondat:

Vibrato rate is defined as the number of fundamental frequency (F0) and amplitude pulses per second.

The Effects of Emotion on Acoustic Characteristics of Vocal Vibrato in Trained Singers

...Vibrato rate is defined as the number of fundamental frequency (F0) and amplitude pulses per second (Seashore, 1931). Frequency modulation (FM) and amplitude modulation (AM) both contribute to vibrato rate. AM is largely an epiphenomenon that arises from the resonance-harmonic interaction (RHI; Horii, 1989; Horii, 1988). The RHI is the interaction between rising and falling harmonic frequencies, as a result of fluctuating F0, and the formant peaks in the vocal tract transfer function that determine the overall intensity of a sound. This interaction creates an involuntary modulation in amplitude with the modulation in F0 (Horii, 1989; Horii, 1988). It is important to note that there is also a laryngeal component of AM that can be measured through electroglottography (Dromey, Reese, & Hopkin, 2009), although this study will not examine AM, because the target behavior for a singer is the modulation of fundamental frequency. ...

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