They are or they have?

As a newly arrived foreigner in France, you pass through many small difficulties, some hard to imagine for those who have never tried to live outside their own country. One of my small challenges was to hear the difference between they are = ils sont and they have = ils ont.

When you say them, the first one gets a simple S from the word sont and the second one gets a toned S by binding together the two words that is pronounced as a Z.  I had major problems in hearing that difference!

Funny thing about this is that in Swedish we have the letter Z in our alphabet, but we seldom use it and pronounce it as S...  I felt like the Chinese that say L instead of R!

Now I hear the difference very clearly, in fact so clearly that it is difficult for me to understand how I ever could fail to hear this difference....