Very cool. Yes, you need headphones, or subwoofer-like capability in your speakers. Even when the seismometer is buried, it may pick up the same sounds, from the wind over the panels, transmitted through the spacecraft and into the ground. Wind can be a significant contributor to noise in seismometers. Many in Alaska are only buried a few feet - as deep as one can dig during a half-hour of helicopter time. The Japanese have their seismometers 100 feet underground in cement vaults.