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# peakPower(forChannel:)

Returns the peak power, in decibels full-scale (dBFS), for an audio channel.

```
func peakPower(forChannel channelNumber: Int) -> Float
```

## Parameters

`channelNumber`

The audio channel with the peak power value you want to obtain. Channel numbers are zero-indexed. A monaural signal, or the left channel of a stereo signal, has channel number `0`.

## Return Value

A floating-point value, in dBFS, that indicates the audio channel’s current peak power.

## Discussion

Before asking the player for its peak power value, you must call [`updateMeters()`](/documentation/AVFAudio/AVAudioPlayer/updateMeters()) to generate the latest data. The returned value ranges from `–160` dBFS, indicating minimum power, to 0 dBFS, indicating maximum power.

---

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