Stutter

The following material is Open Game Content from a 3PP Source

STUTTER
School enchantment [mind-affecting]; Level bard 1
Casting Time 1 standard action
Components V, S
Range close (25 ft. + 5 ft./2 levels)
Target one creature
Duration 1 round/level
Saving Throw Will negates; Spell Resistance yes

If the target fails a Will save, she begins to stutter. The target will suffer a -1 penalty to all Charisma-based skill checks for the duration of the spell. The penalty increases by an additional -1 for every two caster levels beyond 1st (maximum of -5). In addition, spellcasters will not be able to cast any spells with verbal components, and bardic performances that rely on vocalization – be it song or oratory – will not work.