That is a common problem in Duolingo, Polen, read without context can be pronounced in both ways. Which I guess is done with the words in duolingo. This is the case for some English words as well, export, read, wind, live, tear...
What we hear here is the way you would say (nord-/syd-)polen = the (North/South) Pole. Or the borrowed English world the pool, which in correct Swedish would be simbasängen.
The voice is not quite perfect on this sentence, as of September 25th, 2017, so I've taken the liberty of re-recording it.
Like Helen noted above, the first vowel in Polen is incorrect, effectively turning the meaning into "The book will be printed in the (swimming) pool."
Please find a correct recording on http://duolingo.vydea.io/5bc27ed1f1b44991a808c11f8a24e6e6.mp3
For more info on re-recordings, please check the info thread: https://www.duolingo.com/comment/23723515
Thanks for listening. Ha en bra dag! :)