You may be wondering why we should have a slider for Spatial Blend, instead of a checkbox. This is because we need to fade between 2D and 3D, and there is a good reason for this. Imagine that you're in a game and you're looking at a screen on a computer. In this case, your camera is going to be fixated on whatever is on the screen. This could be checking an inventory or even entering nuclear codes. In any case, you will want the sound that is being emitted from the screen to be the focal audio. Therefore, the slider in the Spatial Blend parameter is going to be closer to 2D. This is because you may still want ambient noises that are in the background incorporated into the experience. So, if you are closer to 2D, the sound will be the same in both speakers (or headphones). The closer you slide toward 3D, the more the volume will depend on the proximity of the Sound Listener to the Sound Source. It will also allow for things, such as the Doppler Effect, to be more noticeable, as it takes in 3D space. There are also specific settings for these things.