Vocalize

This spell allows the recipient to cast spells that normally require a verbal component without the caster needing to make a sound. Such spells must be cast within the duration of the vocalize spell. This spell is also useful in situations where quiet is desired, or when the recipient is under the influence of a silence spell.

Vocalize does not negate a Silence spell, but merely offsets it for the purpose of spell casting; if a spell caster under the effect of vocalize casts a spell that has some audible effect, that sound will be masked for as long as silence remains in force. Vocalize does not affect normal vocal communication.

(transcribed from the 2e Wizard's Handbook)