Wordnet 3.0
VERB (1)
1. 
 make a deep hollow sound; 
- Example: "Her voice booms out the words of the song"[syn: boom, boom out]
WordNet (r) 3.0 (2006):
boom out
    v 1: make a deep hollow sound; "Her voice booms out the words of
         the song" [syn: boom, boom out]