Something muted has a softened tone or quieted sound. When you try to listen through the wall at what someone is saying, it's really muted and mumbly, even if you put a glass to your ear.
When you mute the TV or computer speakers, all of the sound goes quiet, but something described as muted is just toned down or turned down. When you whisper you speak in a muted voice; it's not completely quiet or no one would hear you, but it's quiet enough to muffle the sounds or secrets you share. Muted colors don’t stand out as much as bright ones. Beiges and soft grays are muted, and they're great for showing off bright contrasts like a turquoise scarf or red tie.