The quality of the recording is to some extent the fault of the speaker, because she can't use her good microphone or her post processing software with Duolingo, but there is also Canadian raising, the reason Americans hear Canadians say "aboot." I have re-recorded to ensure you can hear the Ts, in any case. Keep pointing these out. I appreciate it.
I think there is reprocessing, perhaps both data compression and manipulation of the dynamic range. Often when I listen to a recording in the course I don't know why I would have accepted that quality in the first place.