Yes actually; your sound file must be in a .wav format, with (what i think is the safest) a sample rate of 44,100Hz and only a mono channel. Also, make sure there are no "regions" in your sound file or else it may loop unnecessarily no matter whether you turn it off or not. When searching for it under the "sound resource browser" make sure the sound type is set to "Raw" and if it doesn't show, you may would need to close Hammer, or even Steam and restart them, it should appear!