Digital Workshop

We've produced a presentation for a client.

It's got voiceover on channel 1, and background music on channel 4.

It also includes some mpg clips.

He's just written this:

"Part way through playing, I lost some of the sound. I still get the background music playing clearly, but the voiceover and audio tracks from the video clips are very muffled. Odd thing is that this only applies when outputting from the headphones socket. It's fine on the laptop internal speaker."

DW.... is there any possibe technical reason for this? Obviously it doesn't happen on my test pcs.

His headphones are broken! (Or the headphone socket)

Seriously - there is no way the output method could have any effect on the sound.