|index||The index of the sound to get the gain of.|
This function will return the current gain value for the given
sound. The sound can either be one referenced from an index for an
individual sound being played which has been stored in a variable
when using the audio_play_sound or audio_play_sound_at
functions, or an actual sound asset from the resource tree.
if audio_sound_get_gain(snd_Music) != 1
audio_sound_gain(snd_Music, 1, 0);
The above code will change the gain of the audio played from the sound indexed as "snd_Music" if its gain is not equal to 1.