Yes, if a sound doesn't load (the LoadSound() function returns 0), it means that no sound card is present (assuming the file you are trying to load does exist).
The sound functions are not meant to cause an error, even if you pass 0 to them instead of a valid loaded sound, so you shouldn't really have to detect whether a card is present or not.
The sound functions are not meant to cause an error, even if you pass 0 to them instead of a valid loaded sound, so you shouldn't really have to detect whether a card is present or not.