PSA: a heads-up re the Speech API on the Mac

[Avi Drissman]

The current implementation of the Speech API on the Mac uses the NSSpeechSynthesizer API for the platform voices. That is a deprecated API, and one of its particular weaknesses is having an absolute fixed rate on the synthesizer rather than relative rates. What that means practically is that the platform voices currently speak about 1.2× to 1.5× too fast. Not all the voices speak too fast, though; the "Google" voices that ship with Chrome do not have this problem.

I'm going to be switching to a new (non-deprecated) API, AVSpeechSynthesizer. This new API does not have this existing weakness. In particular:

- On Chrome Mac, all voices (platform and Google) will now match in speed

- The platform voices in Chromium Mac will now match the speed that Safari uses

- The platform voices in Chromium Mac will now match the speed of voices across other platforms

- The platform voices in Chromium Mac will now match the intent of the spec (where "1" means the default speed)

Avi