The sound file has apparently degraded. Instead of starting with "Is" there is a clunk sound so that the first word heard is aoibhinn. Duolingo appears to be trying to hint that sometimes the copula is left off?
You might want to try a different browser - the is is quite distinct on my computer.
Most browsers have an option to play a sound file back at half speed - this is a direct link to the audio from this exercise, and if you right-click on it you can set the Play Speed to 0.5. (Firefox doesn't do a great job with this, Microsoft Edge is far better)
Tuigim. I'll try Edge to see if that helps. If I click replay a few more times, sometimes the copula does come through. On other sentences, sometimes the audio stops before the sentence is done so I know then to click play again and then it plays everything.