https://opentextbooks.rug.nl/americanenglishphonetics2/chapter/6-2-tense-and-lax-vowels/
6.2 Tense and lax vowels – An Introduction to American English Phonetics
GA vowels can be divided into two groups: lax vowels, which can only occur in closed syllables (ending in a consonant), and tense vowels, which have no such...
an introduction tolax vowelsamerican englishtensephonetics