When the Wither Storm approaches the player, this sound will play:
The Wither Storm Approaches sound.zip
.

And only if the player catch sight of Wither Storm's silhouette in distation

I feel like this sound would be too intrusive but could be in combination with music that is played when looking at the WS from a distance. A version of the sound without the WS ambience in the background would be necessary if this feature would come to fruition however.

Closing as I personally feel this sound wouldn't really fit in.