Audio pickup
An audio pickup was a listening device.

In 2367, Reginald Barclay created a neural scan interface that communicated his thoughts directly to the 's central processing unit. This meant much of his higher brain functions and memory were transferred to the starboard computer core while his body remained in the holodeck. 

As a result, Lieutenant Commander Geordi La Forge disconnected the audio and visual pickups inside the observation lounge so that the senior staff could talk privately without being monitored by the ship's computer/Barclay.

Later on the bridge, Captain Jean-Luc Picard gestured Lieutenant Worf to disconnect audio before ordering a security team to Holodeck 3 to disconnect Barclay from the computer. ()
Sensor technology
Computer technology