Support for Neural voice engines on Amazon Polly

[jmernin]

I find some of the Amazon Polly voices are a little too fast for non-native English speakers to understand easily, but the Neural version of those same voices is that little bit slower and seems to work better for them.

Therefore, I've been trying to determine if there's a way to specify the Neural engine for the voice I've chosen but I'm not sure this is possible at present. Is it?