HF Connector - Replace parts in a Nexus S
At first note that the i9023 is the Nexus S (with S-LCD) and not a Nexus One.

Here's iFixit's teardown.

Here's what iFixit says: The EM-Tech EME1511AFRC integrates the earpiece speaker, loudspeaker for speakerphone and media use, and a sensor bank all into one unit with a singular shared data connector.

That sensor bank includes at least the proximity sensor, a light sensor (for LCD dimming) and maybe some of the rest of the sensors (accelerometer, gyro, compass).