Translation of "わかるんだ" in English

今はっきり わかるんだ

I see it now so clearly

彼の頭の中では、世界がくるくる回っているのがわかるんだ。

The eyes in his head see the world spinning round.

絶対音感のある人は、耳で聞いただけでどの音かがわかるんだって。

They say that a person who has perfect pitch can tell just by listening what pitch a note is.

- 健康を害してはじめてその価値がわかるものだ。
- 体を壊して初めて、その大切さがわかるんだよ。

- It is not until you have lost your health that you realize its value.
- It isn't until you have lost your health that you realize its value.
- It's not until you have lost your health that you realize its value.