As per Silence:
Upon the casting of this spell, complete silence prevails in the affected area. All sound is stopped: Conversation is impossible, spells with verbal components cannot be cast, and no noise whatsoever issues from, enters, or passes through the area. The spell can be cast on a point in space, but the effect is stationary unless cast on a mobile object. The spell can be centered on a creature, and the effect then radiates from the creature and moves as it moves. An unwilling creature can attempt a Will save to negate the spell and can use Spell Resistance, if any. Items in a creature’s possession or magic items that emit sound receive the benefits of saves and Spell Resistance, but unattended objects and points in space do not. Creatures in an area of a silence spell are immune to sonic or language-based attacks, spells, and effects.
I'm the DM. When a boss gets low on HP, I'm considering to attempt letting her cast Silence, and then use her own Spell Resistance for the purpose of getting to use spells with Verbal Components.
The description seems to account only for direct targets of Silence. The line says:
Spell Resistance: yes; see text or no (object)
which isn't exactly enlightening. 3.5 doesn't exactly show intent either.