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# kAUVoiceIOProperty_MutedSpeechActivityEventListener

A property to register a listener that the system calls when it detects speech while the user has the microphone muted.

```
var kAUVoiceIOProperty_MutedSpeechActivityEventListener: AudioUnitPropertyID { get }
```

## Discussion

To use this API, your app must implement mute using the [`kAUVoiceIOProperty_MuteOutput`](/documentation/AudioToolbox/kAUVoiceIOProperty_MuteOutput) property.

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