I have hundreds of video clips shot during a voyage. I process them using Sony Vegas Movie Studio 8. For each clip I remove the sound track and replace it by my own narration. Then these clips are produced as MPEGs for further processing using DVD Architect. But when I play the DVD in the majority of the chapters there are audio problems. The voice comes with echos as if somebody is shouting in an immense theatre hall. I examined the audio tracks that cause trouble and the ones that are normal using audacity. They are all stereo 48000 Hz 32 bit floating point. I see no difference between them. What is the origin of this problem? Help is urgently needed. Thanks.