How can I fix this?

[gil900]

Hello,
I am looking for tool for fixing what happening in 00:00:00.376
I need a tool that will make a smooth transition between the echo sound(00:00:00.176-00:00:00.396. Hope it's the word in English) to the background noise
Something is sound wrong in 00:00:00.383-00:00:00.495 and it is hard for me to fix it manually.

If there is some tool that make it smooth then I would love to know about it.

Thanks.