---
title: kAudioUnitProperty_TailTime
framework: audiotoolbox
role: symbol
role_heading: Global Variable
path: audiotoolbox/kaudiounitproperty_tailtime
---

# kAudioUnitProperty_TailTime

A read-only Float64 value valid on the audio unit global scope.

## Declaration

```swift
var kAudioUnitProperty_TailTime: AudioUnitPropertyID { get }
```

## Discussion

Discussion Indicates a time estimate, in seconds, between the last valid input being received by an audio unit and the audio unit’s output becoming silent. For example, a reverb unit’s tail time estimates the “decay” time. The tail time value is usually a conservative estimate that you can depend on.

## See Also

### Properties

- [kAudioUnitProperty_ElementCount](audiotoolbox/kaudiounitproperty_elementcount.md)
- [kAudioUnitProperty_SupportedNumChannels](audiotoolbox/kaudiounitproperty_supportednumchannels.md)
- [kAudioUnitProperty_AudioChannelLayout](audiotoolbox/kaudiounitproperty_audiochannellayout.md)
- [kAudioUnitProperty_AudioUnitMIDIProtocol](audiotoolbox/kaudiounitproperty_audiounitmidiprotocol.md)
- [kAudioUnitProperty_AUHostIdentifier](audiotoolbox/kaudiounitproperty_auhostidentifier.md)
- [kAudioUnitProperty_BypassEffect](audiotoolbox/kaudiounitproperty_bypasseffect.md)
- [kAudioUnitProperty_ClassInfo](audiotoolbox/kaudiounitproperty_classinfo.md)
- [kAudioUnitProperty_ClassInfoFromDocument](audiotoolbox/kaudiounitproperty_classinfofromdocument.md)
- [kAudioUnitProperty_CocoaUI](audiotoolbox/kaudiounitproperty_cocoaui.md)
- [kAudioUnitProperty_ContextName](audiotoolbox/kaudiounitproperty_contextname.md)
- [kAudioUnitProperty_CPULoad](audiotoolbox/kaudiounitproperty_cpuload.md)
- [kAudioUnitProperty_DependentParameters](audiotoolbox/kaudiounitproperty_dependentparameters.md)
- [kAudioUnitProperty_ElementName](audiotoolbox/kaudiounitproperty_elementname.md)
- [kAudioUnitProperty_FactoryPresets](audiotoolbox/kaudiounitproperty_factorypresets.md)
- [kAudioUnitProperty_FastDispatch](audiotoolbox/kaudiounitproperty_fastdispatch.md)