In case you are wondering when to use "i", "om", or "på" en timme:
- i en timme = lasting for a duration of an hour, as in "we'll stay for an hour"
- om en timme = in an hour, as in "we'll leave in an hour"
Those are simple. på en timme means that something will take an hour to accomplish. For instance: vi kan flyga dit på tre timmar = (literally) we can fly there in three hours = (idiomatically) it takes us three hours to fly there.
It's also used for negating durations. For instance:
- När kommer du? (When are you coming?)
- Om en timme! (In an hour!), or
- Inte på en timme! (Not in an hour!)
In English, an hour and one hour have different connotations of precision. Which is 'en timme' closer to?
If you want to point out that it is one hour you could put more stress on 'en' than the computer voice does here.
The forvo guy seems to pronounce "gym" the English way (≈ like "Jim" as you said). It's normal to pronounce it the Swedish way and TTS is ok here. You can compare to and pick the first part of
Not very tolerant of typos, this one. Any chance of an almost correct for "The gym opens in an hours?"
I don't think so. This is decided by Duo centrally and it works the same for all courses, so we as course contributors can't do anything about it. The algorithm is that you can have one letter wrong so long as it doesn't turn into another word.