I use the double speed after hearing the challenges once at normal speed. I have worked my way up from X 1.5 to X 2 so much so that It’s become normalised to me. I’ve not really utilised the listening exercises though and recently tried them and found on level 1 and 2 listening exercise 25 @ double speed it sounds more like quadruple speed or faster and is quite indecipherable to me and when I slowed it down to half speed the song was in slow mo but the speech was around double. Sorry to be trawling over old ground but Is this a glitch @aran or are the listening exercise speeds meant to be much much faster than the double speed I use in the challenges? I use the ios app on my phone btw.
If it’s not a glitch then fine I have some serious chipmunk-ing to catch up on. 
Nope, they’re just double speed too - what’s probably making it feel worse is that the last listening exercise of each Level has got everything that’s been covered in it, so the breadth of content makes it all feel more out of control than the far more predictable individual lessons.
But keep with it - do the last listening exercise from each level every day, like brushing your teeth, and you’ll see some important changes in the next 2 or 3 weeks… 
Wow I was almost certain it was a glitch. I shall be listening everyday and see what happens. 
I’d have bet that 25/Level 1 listening practice was just slightly faster than normal speed (say 1.5x max).
But I agree with @Macky on 25/Level 2: it seems way faster, like 3x-4x!
I can’t believe it’s just 2x @aran! 
…altered perceptions! 
gonna try this. I’ve been listening to them all on the train in to work need to practice before my holiday in Aberystwyth 