I'm learning German and I'm looking for audio examples of the German vowels in Standard German. I know in principle no two people pronounce things exactly the same, but just some examples of someone trying to do the Hochdeutsch pronunciation of the vowels would be great.
I would like to have just the vowels (not whole words), i.e. like here: https://linguistics.ucla.edu/people/hayes/103/Charts/VChart/
He has all the German vowels there, but I think they are some cardinal vowels (i.e. some standardized examples) and don't correspond exactly to the German ones, for example the [ɐ] there sounds different to me comparing it to German.
My idea is to train the vowels, because for example in the word Referendum [ʁefeˈʁɛndʊm], I don't distinguish any difference between the [e] and [ɛ], which I assume would give me an accent when speaking (I have a similar problem for example with [o] and [ɔ], not really sure which one I am hearing or saying). So I'd just like to do some dry training with a flashcard app of the sounds until I clearly hear a difference between all the German vowels.
TLDR looking for a Standard German pronunciation audio examples of all the German vowels said in isolation (audio of only the vowel for each vowel).