In seems to me that in Wikipedia's sound samples for the vowel sounds, there's often some vocal fry, especially in the back vowels. Vowels like ɑ æ ä e and to a lesser extent: ɤ o ɜ œ. Do you concur? Do you think these are good samples for understanding the vowel sounds? Is what I'm perceiving as vocal fry part of the basic vowel sounds?
I agree, and I always recommend authoritative samples. The IPA has a page with acknowledged masters of IPA standards – John Esling, John Wells, Jill House and Peter Ladefoged, and you should use those as reference values. This seems to be a feature of many of that person's performances, not a definitional or intrinsic property of the vowels themselves.