Using The Internal Speakers - HP Compaq NC6140 Hardware Manual

Using the Internal Speakers

The internal speakers play sound in stereo from applications, the
operating system, games, drive media, the Internet, and other
sources.
If an external device, such as a headset, is connected to the
audio-out jack, sometimes called the line-out jack, the internal
speakers are disabled.
Identifying the internal speakers
Hardware Guide
Audio and Video
5–3