Sonic grenades are a United Nations Space Command explosive. Several of them were used in the obstacle course set up by Colonel James Ackerson for John-117's and Cortana's first test with smart AI integration with the MJOLNIR Mark V armor on Reach, hidden amongst the Pillars of Loki and used in conjunction with napalm grenades.
List of appearances
- Halo: The Fall of Reach (First appearance)
- Halo: The Fall of Reach, Chapter 27