kSpeechVolumeProperty

Get or set the speech volume for a speech channel.

Declaration

let kSpeechVolumeProperty: CFString

Discussion

The value associated with this property is a CFNumber object that specifies the speech channel’s speech volume.

Volumes are expressed in floating-point values ranging from 0.0 through 1.0. A value of 0.0 corresponds to silence, and a value of 1.0 corresponds to the maximum possible volume. Volume units lie on a scale that is linear with amplitude or voltage. A doubling of perceived loudness corresponds to a doubling of the volume.

This property works with the CopySpeechProperty(_:_:_:) and SetSpeechProperty(_:_:_:) functions.