Also, these are cost prohibitive to use in apps widely or without limitations. Currently, Google Speech to Text is relatively cheaper at $1 for 166 messages. Source: https://cloud.google.com/speech/pricing
I can't see anything that says how IBMs minutes are done though, whether every message is rounded to 1 minute or not. Edit - based on a comment from someone at IBM in this thread, they're not rounded up to a minute, rather only at the end of the month is the total time rounded. I can't see how they'd be more expensive than google.
* $29.95 to register
* $9.95 per month subscription which entitles you to $14.00 worth of free transcription per month
* $3.50 per page (double-spaced, 225 words) for any pages in excess of your $14 allocation
$14 is four 225 word pages, so, 1-900 words for $0.11 per word, then $1.55 per word. Ish.