Cord Closure!
Singers! An exercise for all singers: sing the song chopsticks in a very staccato 16th note dilineated or separated fashion, somewhere between vowel Eh (bed) and Ay (letter A), in the middle of your voice and then in your high voice. Then use different vowels, but not necessarily ah ( not "forbidden" just not the best for the higher voice above the second passagio). Enjoy!