There are many ways to control how the sound is heard. You learned that there are effects that can be checked and used, but there are also functions to improve the audio. Using these functions in-game will help you get a better understanding of the function and is highly suggested.
Sound Functions
sound_play(Sound Index) Plays the specified sound once
sound_loop(Sound Index) Plays the specified sound until it is stopped, via the stop function
sound_stop(Sound Index) Stops the specified sound from playing
sound_stop_all() Stops all sounds playing at the time
sound_isplaying(Sound Index) Returns true or false(1 or 0) if a sound is playing
sound_volume(Sound Index) Allows you to set the volume of a sound
sound_global_volume(Sound Index) Allows you to change the global volume of all sounds
sound_pan(Sound Index) Allows you to change the sounds pan settings
sound_fade(Sound Index, Value, Time) Allows you to change the volume to number indicated in set amount of time
sound_background_tempo(Value) Changes tempo of music set as background music
sound_set_search_directory(Directory) Sets directory music will be found in