3-dimensional sound? Well, if you close your eyes and move your mouse around, you can sort of hear where your is. How does this work? Your ears can detect where sound is coming from by hearing the volume difference between your ears, and also the timing difference (due to the speed of sound), but that is not included here (i might make that later though). If you want to use this, backpack the script in the 'Speaker' sprite and put it in your project and change the sensing blocks for distance and x position to the sprite you want to "listen from". Also make sure to give me credit! Yeah that sound ...
I came up with this myself, it's pretty simple.