Ven has forgotten the soundfile :
Code:
engfunc(EngFunc_EmitAmbientSound, 0, origin, sound, VOL_NORM, ATTN_NORM, 0, PITCH_NORM)
If you want the sound to be heard in the whole map, set the attenuation to ATTN_NONE, but in that case, spk command will do the same except the sound won't be located.
You still need to make a task if the sound doesn't loop by himself as i wrote in my first post.