Lieutenant Pierson was a Starfleet engineer serving aboard the USS Enterprise-D in 2369.
Pierson worked in the systems monitor room, and was heard paging Lieutenant Commander Geordi La Forge while the Enterprise-D was in orbit of Tyrus VIIa. (TNG: "The Quality of Life")
This character appeared as an off-screen voiceover.
Judging from the area Pierson was assigned, this may indicate that he was, more specifically, a systems engineer