I translated this as ”Where is the harmony of your voice” and it was not accepted. ”In” would have been better, but so far duolingo seems to be insisting on ”from” as the translation of ”din” in every example regardless of the context, and the result is totally unnaturual English.
In English, we would never say "the harmony from within your voice," though I suppose it is grammatically acceptable. Rather, it has to do with how we understand "from within" and how we understand harmony. When we say something comes "from within," we are picturing movement. The bees are coming from within the hive, a smell is coming from within the oven, or a sound is coming from within a box. Here, it really should be "in," rather than "from," because the harmony is a characteristic inherent in your voice, like the beauty in a rose or the injustice in a system. Neither of those, for instance comes from within, as it never leaves the thing it is in.