Translation:The birds are flying over the ocean.
It's helpful to know that "au-dessus" is not pronounced as three syllables, but only two, i.e., odsy. Maybe the hyphenated word confuses the computerized TTS. Compare also to the word for "below/under/underneath", au-dessous, pronounced odsu.
In the audio there's no 'liaison' when the speaker says 'les oiseaux' it's exactly pronounced as 'le oiseau', why is it like that?
The female voice still doesn't pronounce the liaison (October 2018).
Correct, but it does sound different to le oiseau given the vowel in les is different.
True, but Brits would say "sea" even if the birds were flying above the Atlantic. I think the only times we tend to say "ocean" are when referring to "the world's oceans" or a specific ocean.