What is the difference in pronunciation between
le livre rouge
and--
les livres rouges
?
What is the difference in pronunciation between
le livre rouge
and--
les livres rouges
?
In this case, only the distinction between articles le (pronounced /lə/) and les (pronounced /le/ or /lɛ/) marks the difference.
In most cases, the added s does not change the pronunciation, but sometimes a liaison between an adjective and the noun may change:
un grand espace
/œ̃.ɡʁɑ̃.(t‿)ɛs.pas/
de grands espaces/də.gʁɑ̃.z‿ɛs.pas/la grande ère glacière
/la.ɡʁɑ̃.d‿ɛʁ.ɡla.sjɛʁ/
les grandes ères glacières/le.ɡʁɑ̃d(ə).z‿ɛʁ.ɡla.sjɛʁ/
And as always, the occasional exceptions.