It's funny, but when I talk to local Singaporeans, many say they have never seen the bird that’s so distinctively loud. Turns out the bird is called an Asian Koel. I've found it a few times now and this time happened to have a camera with me so I got a video for anyone who is still wondering what it looks like. (Wish I had better zoom so you could see the red eyes).
It's rather like a small crow with a long tail. All black with a call that makes it hard to tell where it's coming from. While many are annoyed by its loud voice, I find it as a perk of living in this beautiful country. The bird is simply doing what it does and has done for ages. I figure it's most likely making the sound to find a mate. (So glad yelling isn't an accepted practice for humans looking to do the same!)