Sound Problem

[FamousPker49]

Okay, I was looking around for that cliche bomb whistling then explosion, or hell even just the whistle, so I googled some free sound sites and found what I was looking for. But for some reason when I import into WE and go into the sound editor, it says it appears to be an invalid sound file. Any ideas?

I have attached the sound in question.

 

[Samuraid]

It's 4-bit audio. I think Warcraft 3 needs either 8-bit or 16-bit.

Here's the same file in 16-bit: