As well as looking at the vowel system of a specific language, ie English vowel phonemes, there is also a way of describing vowels irrespective of language, ie phonetically. One system of such vowel reference positions is called the Cardinal Vowel system. The Cardinal Vowels can be used to plot the exact location of vowels in any specific language.
Use the interactive chart below to familiarise yourself with the IPA vowels.
Chart reproduced with permission from Eric Armstrong's Voice and Speech website (see Resources section).