How do I make the sound quieter when I move away from the block?

I downloaded MCreator today. The first idea was to create a mod with a block that makes a sound. And it turned out that the block makes a sound, but when I move away from it in the game, it does not fade smoothly, but abruptly ends. How do I make the sound fade out? Please help me. Once again, I apologize for my English, I simply do not know it.