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# kAudioSessionProperty_InputGainScalar

A read/write `Float32` value that indicates the audio input gain setting for the active input source.

```
var kAudioSessionProperty_InputGainScalar: Int { get }
```

## Discussion

The range for this value is `[0.0, 1.0]`, as follows:

- `0` indicates the lowest audio input gain setting
- `1` indicates the highest audio input gain setting

Attempting to set a value outside this range results in the value being clamped to this range. This property’s value is valid only if audio input gain is available (see [`kAudioSessionProperty_InputGainAvailable`](/documentation/AudioToolbox/kAudioSessionProperty_InputGainAvailable)).

If no app with an active audio session is using this property for a given input source, the system restores the default input gain setting for the input source.

You can employ an [`AudioSessionPropertyListener`](/documentation/AudioToolbox/AudioSessionPropertyListener) callback function to listen for changes in this property’s value.

---

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