I recall Brian Blessed (who voiced Boss Nass) gave an interview where he said “I tried to make sure my noises didn’t interfere with dialogue”. He basically said that he thought that Jar Jar sometimes made noises on the line, and he has a lot of plot, so the audience would go, “What’s he saying? What did he say?” Anyway, I’m not saying Brian Blessed should be the authority on this, but I think it is a fair point.
This is exactly why I don’t like Jar Jar. His antics and his voice would be tolerable if you could actually understand what he was saying. Every relevant thing that he says is covered up with babble for no reason.