> For the complete documentation index, see [llms.txt](https://docs.hology.app/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.hology.app/zh-tw/gameplay/sound/audio-parameter.md).

# Audio parameter

It is possible to pass in an audio asset to an actor as a parameter in the editor. This makes it possible to easily change the sound that an actor plays from the editor.

The code below illustrates how to define an audio parameter.

1. First define the parameter. Read more about parameters in [演員參數](/zh-tw/gameplay/yan-yuan-actors/yan-yuan-can-shu.md)
2. Inject the View controller to access the global audio listener.
3. Create the instance of a new sound instance to be able to play the audio clip.
4. Set the sound buffer using the value of the audio parameter in the `onInit` function. At this point the parameters are set. Read more about actors lifecycle functions  in [Actor 的生命週期](/zh-tw/gameplay/yan-yuan-actors/actor-de-sheng-ming-zhou-qi.md)
5. Finally, we define a function that can be called on the actor to play the sound which could be called whenever the sound should play.

```typescript
import { Actor, BaseActor, ViewController, inject } from "@hology/core/gameplay";
import { Parameter } from "@hology/core/shader/parameter";
import * as THREE from 'three'

@Actor()
class ExampleActor extends BaseActor {
  @Parameter() audio: AudioBuffer;
  private view = inject(ViewController)
  private sound = new THREE.Audio(this.view.audioListener)

  onInit() {
    this.sound.setBuffer(this.audio)
  }
  
  playSound() {
    this.sound.play()
  }

}

export default ExampleActor

```