This is a writeup about one of the Sharif University CTF steganography challenge.
The title for this steganography challenge was a big hint. We have a WAV file, so things come pretty straightforward, we have to visualize sound.
We already saw this steganography technique earlier so the first idea which came to our mind was to display the frequency spectrum of the audio file, and it was right. You can use a free software like Audacity to display the frequency spectrum.
The flag was indeed visible inside the the frequency spectrum.