An .snt file is just a file that gives info about the sound. For example:
<SOUNDENTITY>
<SOUNDS>
<Main>
<Sound File="player_bodyfall1" />
<Sound File="player_bodyfall2" />
<Sound File="player_bodyfall3" />
<Sound File="player_bodyfall4" />
<Sound File="player_bodyfall5" />
</Main>
</SOUNDS>
<PROPERTIES Volume="1" MinDistance="1" MaxDistance="10" Random="1" Interval="0" FadeEnd="False" FadeStart="False" Stream="False" Loop="False" Use3D="True" Blockable="True" BlockVolumeMul="0.7" Priority="0" />
</SOUNDENTITY>
I think there's a specific script function that lets you play a sound without a .snt file, but I can't think of it right now. You do need a .snt file for your sound otherwise.