Will my neighbor hear me singing if the apartment is 鉄筋コンクリート造?

I just moved to Tokyo. The apartment is new and 鉄筋コンクリート造 (sorry Idk how to say it in English), with very good sound insulation. I hear no sound neither from outside nor from my neighbor.

Sometimes I just want to sing to vent, without a mic and with the ordinary volume of singing a song, but worrying if my neighbor would hear me. So I just want to ask, what's your experience if you live in an apartment made by 鉄筋コンクリート?