When stereo sound was introduced to films in the 50s, dialogue was routinely panned from left to right on screen to match the action. This has dropped mostly out of use, mostly due to the fact that we perceive aural location changes as much more jarring than visual cuts. It\'s possible that we could be trained to get used to these cuts just as we accept the visual ones. But for now the standard has become to leave speech centered on the audio channel, regardless of the location of the source in the picture.
It is occasionally used for certain purposes:
- Lines from off-screen characters are sometimes panned to whichever side is appropriate
- Dialogue lines that are well separated from others in time and for which the speaker is well off-center can be panned
- Slight panning off center for 2 characters speaking to each other is occasionally used
