Want the problems with my neighbor to end.

I never thought I would try something like this, but my situation is just getting worse despite me trying to avoid it.

I spend a lot of hours in one of the divisions of my home, at the computer, talking a lot, and used to be at late nights around 8pm to 11pm but then the problems with my neighbors started. 

He called the police several times, but they were hearing nothing out of the ordinary, but I still decided to continue just by lowering my voice and any possible noises, but eventually, I just had to just stop doing any talking while on the computer after 8pm.

Now, after not being able to attend the Building Meeting, I saw that he now says that the night time got better but during the day is not just a normal day activity or sound for the building.

I don't listen to music on speakers, I don't shout, I just talk. He has been bad mouthing me around the building and I decided to take some action with a help of a lawyer.

I still want to solve this problem the "easier" way, by soundproofing my office, but that is a big cost for the monthly wage I have. So I'm here asking for the help of those who might wanna lend some help.
This is having a tremendous impact on my life and performance.

Thank you for Reading.

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The Quote is in Portuguese. Its just showing the price for soundproofing the entire room, 4 walls + Floor + Ceiling.

ps.I will be sure to update photos of the soundproofing as soon as we hit the goal.