Bonjour Brian,

I remember how frustrating it can be when improving your listening skills whilst learning a foreign language. Having listened to the audio, 'lui' is said a tiny bit fast (the 'i' sound is a bit "swallowed") and therefore sounds a tiny bit different to a non-native ear. A B1 recording will not be as clear as a lower level one (the speed / articulation will be closer to how a native speaker talks) so some sounds will not be as clearly enunciated as in a lower level recording. Practice makes perfect, I guess ! ;-) 

I hope this is helpful.

Bonne journée !