App to play MP3 music by voice command?

[gf1701]

I sometimes use my phone as an MP3 player, playing music files I've downloaded to the device. So far, I've been using Google Play Music. I was wondering if there is a way to play my music by using only voice commands. I did some searches about this, and saw references to using Google Now to do it. So I tried "Okay Google" and told it to play a particular title. After telling it to use the Play Music app, it did so without future prompts, but it never looked for the titles I requested on my device, instead always going online to search for a match (and never getting the right one). I tried adding "from my files" and "from my device," to no avail. So is there an app out there that can do this, play the MP3 file I request with voice command only? - Gary