Page 1 of Simpson S4 R2 dvd sound problem in Marge in Chains episode?

I watched all R2 episodes but i noticed that in Marge in Chains at 03.14 at the Osaka plant when the japanese are laughing and there is a mute on the sound for a few seconds. I have check on the same episode i taped from BBC2 and there is nothing wrong it. So Fox has made error ? It is out of synch too?

I noticed the same problem on the Region 1 release, they should continue laughing and then cough but instead they laugh then it goes quiet, very strange.