I need to be able to interpret the values in AVSpeechUtterance's rate parameter as words per minute. It looks like it is just an opaque 0.0 - 1.0 value with 0.5 as the default.
The old NSSpeechSynthesizer API lets you specify a rate as words-per-minute, but there doesn't appear to be any mapping to the new values.
Should I just file a Feedback request for this feature? I'd be fine if there was just some sort of API to return the WPM for a given rate value (or visa-versa), or even just document a multiplier equation I could use to do the mapping.
Or maybe it ever varies depending on the voice?
If we can't have words-per-minute, even just a way to figure out a multiplier (where 1x is the default speed, 2x is 2 times the default speed, etc) would be helpful. We just want some kind of text label describing the speed, in units that make logical sense to a user, and that can be exposed to accessibility.
0.0 / 0.5 / 1.0 just isn't terribly descriptive.