I switched from my Dell pc and tested with different earphones on Android devices. Now I can hear it more distinctly and realize that she is starting the first s they way I was taught to say words starting with t and d. So there is nearly no "hiss" sound such as an English word like "sister" would sound in America.
Interesting discrepancy then but not the first that I've had with Duolingo. I tried saoirse on teanglann.ie and the word is clear as a bell. So it's not a degradation of my hearing as I first suspected. I think it might be a technology conflict in the audio coding vs. decoding. The t and d are "dental" consonants in Irish and sound slightly different than American English palatal versions. I thought perhaps she is making that initial "s" a dental version because it follows tá.
It happens; it takes time for the course creators to review every problem reported to them, determine whether the reported problem really is a problem, and to fix it if it is. Some problems can’t be fixed until Tree 2.0 is grafted in, since Duolingo keeps certain aspects of the courses locked most of the time — even locked to certain types of corrections by the course creators.
In the meantime, you can either enter “freedom” to work with the course as it is, or enter “liberty” despite it not being accepted; if you choose the latter, then you can either keep reporting the problem to make sure that it stays on the course creators’ to-do list (that’s my usual course of action for a similar situation) or stop reporting it.
it's "oo-ing", but "oo" sound is shortened so that you are hearing "wing".
You can try it yourself - try to say "oo-ing" or "oo-een", and then say it faster and faster, and the "oo" disappears, and you end up with just the "w" sound that is the transition between "oo" and "ing"/"een"