die away —(of a sound or light) become weaker or fainter:
- The sound of the car died away in the distance.
die out—
1. (of a group of living things) perish; become extinct:
- If too many of these rare animals are killed, their kind will die out.
2. (of practices, customs, ideas, etc.) cease to exist; disappear:
- It’s time this selfish habit died out.