Audio on Czech course
There is no audio on this course and it is Impossible to advance Programme doesn't allow one to advance without answering the audio questions even if one keeps skipping the audio prompts.
Please report this as a bug: http://support.duolingo.com/hc/en-us/requests/new
Similar issues occur for me in the past few days on other courses when I use the strengthen button on the home page. I have made a post about it here: https://www.duolingo.com/comment/24463610
In my post I have now linked to this post too, although it may be an unrelated issue.
Although not ideal, as a short term measure it should be possible to turn audio off in the settings, which would hopefully prevent the program from giving you listening exercises: https://www.duolingo.com/settings
Just remember to turn the sound on every couple of days to see if it is working yet - the courses are much better with sound than without in my opinion.
It seems that staff are aware of an issue with iOS and are working on a solution as mentioned by nueby here: https://www.duolingo.com/comment/24472494