The Valley of Sound is a very pretty, quiet valley, home of the Sound Keeper.
It is your typical valley, but while the Sound Keeper kept all the sounds, it was silent, which the people hated, but Milo broke the silence with one word, "but", which was the beginning of "but it's not fair."
During the silent period, people communicated by writing and body language. They sent Milo to the sound keeper to retrieve the sounds, which is when he said "but" and got the sound back. Nobody knows why the Sound Keeper decided that there were too many unpleasant sounds and locked all sounds, including the pleasant and neutral sounds, up, but the common hypotheses included the weather, the moon, and the absence of Rhyme and Reason.
Due to the silence, Dr Discord and the Awful Dynne do like it.