Yamaha SY99 Owner's Manual page 80

Increase the modulation
sensitivity for an AFM
element
Pitch Mod Sense (pitch modulation sensitivity) determines how sensitive the
pitch will be to modulation from the LFO.
Press EXIT to return to the Element 1 job directory and select 05:Sensitv
(sensitivity).
PModSens (pitch modulation sensitivity) is adjustable independently for each
operator over a range of 0-7. To create normal vibrato, all operators must be
pitch modulated equally by the LFO. Increase the PModSens equally for all
operators. (If the LFO affects the pitch of some operators more than others, the
harmonic structure of the sound will vary, which can be an interesting effect in its
own right.)
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