fadeIn

fadeIn(id: string, duration: number, startVolume?: number, endVolume?: number, skipDispatchEvent?: boolean): void;

Fade a playing sound's volume from startVolume to endVolume over duration seconds. Use this to smoothly introduce a sound that is already playing.

Parameter	Type	Default	Description
`id`	`string`	—	ID of the sound to fade in
`duration`	`number`	—	Fade duration in seconds
`startVolume`	`number`	`0`	Volume to start from
`endVolume`	`number`	`1`	Volume to reach
`skipDispatchEvent`	`boolean`	`false`	When `true`, suppresses the fade event

tip

You can also trigger a fade-in directly from play() via PlayOptions.fadeInDuration — no need to call fadeIn separately.

Example

await soundManager.loadSounds([{ id: 'tokyo-train', url: 'tokyo-train-melody.mp3' }]);

// Start silent
soundManager.play('tokyo-train', { volume: 0, loop: true });

// Fade from 0 → 1 over 3 seconds
soundManager.fadeIn('tokyo-train', 3);

// Or fade from 0.2 → 0.8 over 2 seconds
soundManager.fadeIn('tokyo-train', 2, 0.2, 0.8);

⏱ Fade Duration3s

0.5s8s

Try it: Adjust the duration and click Fade In to hear the sound gradually rise to full volume.

Example​

Example