Yes this is correct. In the second world war, this was used by british (and perhaps other nations too) government as propaganda. It was reminding people not to talk about secrets that give away information, like blackout curtains, or how they covered up signs of rail stations. also just normal info on how the war was going, because thee were many german spies playing regular british people. Hope this was interesting! EA
No, there's no liaison if the first word ends on the second-to-last consonant's sound and the last one is actually silent. "Murs" is pronounced like the singular "mur" and not "murZ" so you wouldn't make the liaison, but you would on "des oreilles" because "des" ends on the vowel's sound.
In fact, plural noun + verb is an optional liaison. You would pronounce the s in 'murs ont' if speaking more formally. In the case of 'Les absents ont', the s in 'les' is a required liaison but the s in 'absents' is again optional. Therefore you should always hear the first in any register of speech, but not always the second. Of course, native speakers frequently speak so fast that liaison rules disappear!
Same in Serbia!
The walls are listening-Zidovi slušaju
or The walls have ears-Zidovi imaju uši
Which is funny when I think about this- when parents/grandparents/teachers think you're not paying attention, they say ''Dobro,kome ja ovo pričam? Zidovima?'' meaning- ''So who am I telling this [to]? The walls?'' so it's funny we contradict ourselves
It's kind of like saying that you never know who is listening and when they are listening.