fadingsound
nounUK /ˈfeɪdɪŋ saʊnd/
US /ˈfeɪdɪŋ saʊnd/
A fading sound is a noise that slowly gets quieter until you can't hear it anymore.
As the train pulled away, we heard the fading sound of its whistle.
OTHER MEANINGS
2. A sound that gradually weakens in volume or intensity over time.
The fading sound of footsteps told us she had left the room.
3. In audio production, a sound whose volume is gradually reduced.
The engineer added a fading sound effect to end the scene smoothly.
4. A memory or impression of a sound that becomes less clear.
He recalled only the fading sound of his mother's lullaby.