Whisper

You manipulate the air surrounding you so that it mutes sounds.  By controlling the vibrations of the air, you are able to muff any sound to be as quiet as a whisper. For the duration, each creature you choose within 10 feet of you (including you) has a +5 bonus to Dexterity (Stealth) checks. Affected creatures are able to silently cast spells requiring verbal components.

At Higher Levels. When you cast this spell using a slot of 2nd level or higher, the bonus to Dexterity (Stealth) checks increases by +1 for each slot level above 1st. Additionally, the radius increases by 5 feet for every slot level above 1st.