Aerodynamic Investigation of Sources of Vibrato

The role of auditory feedback in sustaining vocal vibrato

“…Rhythmic oscillations have been observed in the activity of laryngeal (Hsaoi et al, 1994;Koda and Ludlow, 1992;Niimi et al, 1988), respiratory (Rothenberg et al, 1988), and articulatory (Inbar and Eden, 1983;Sapir and Larson, 1993) muscles during vocal vibrato and tremor. The source of these oscillations is not well understood.…”

Laryngeal-Level Amplitude Modulation in Vibrato

“…Rothenberg et al 12 suggested that instances of abdominally induced vibrato, which are driven by volitional Psub fluctuations, can be found even among Western classical singers who have been trained to use laryngeally mediated vibrato, in which the CT is primarily responsible for FM, with AM derived from it. The use of an alternate means of generating AM, such as abdominally induced Psub pressure fluctuations, should not be excluded as a possibility among classically trained singers.…”

“…9 Other researchers likewise questioned the ''previously accepted dichotomy'' of FM and AM, suggesting that these categories need further clarification or adjustment. 11,12 Rothenberg et al suggested that ''there may be a number of physiological factors present that might cause a vibratosynchronous variation in acoustic amplitude.'' 12 Horii 5 acknowledged the necessity of delineating AM passively produced through the RHI, and that ''actively produced by singers,'' suggesting that the RHI ''does not preclude'' Psub as an additional mechanism.…”

“…11,12 Rothenberg et al suggested that ''there may be a number of physiological factors present that might cause a vibratosynchronous variation in acoustic amplitude.'' 12 Horii 5 acknowledged the necessity of delineating AM passively produced through the RHI, and that ''actively produced by singers,'' suggesting that the RHI ''does not preclude'' Psub as an additional mechanism. 5 He raised the possibility that still other mechanisms could also be at work; for example, he reiterated Ladefoged's suggestion 13 that pitch modulation is a function of the positioning of the arytenoid cartilages, and intensity modulation is a function of the spacing between them, which contributes to the amount of force used as they come together.…”

“…This type of vibrato is found primarily in non-Western styles, but may also be found in Western classical vibrato to a lesser extent. 12 More recently, Sundberg asserted that there are three possible sources of AM in vibrato. First, the ''amplitude of the strongest spectrum partials, that is, the partial closest to the first formant'' is typically equal to overall amplitude, so that frequency oscillations of particular harmonics toward and away from the first and other formants create proportional amplitude variations.…”