Japanese · Pronunciation Guide
wa-ka-i, three beats — the ka and i are separate morae, so it doesn't end like English "sky."
wakai
A crest on ka and three units of the same length — that is the whole rhythmic description. Two identical a vowels followed by a bare i is a very common adjective shape (compare 高い, 長い), and in every case the final i is a full beat rather than a diphthong's tail.
Listen: 若い
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彼はまだ若いです。
Kare wa mada wakai desu.
He's still young.
Listen: 彼はまだ若いです。
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彼はまだ若いです pairs it with まだ, two short beats, and ends with the devoiced です. Notice how little length there is anywhere in this sentence: no long vowels, no geminates, no nasals. That makes it a pure evenness drill — eight or so short morae in a row at a constant tempo.
"wa-KIGH" is the standard collapse: the second and third morae fused into the English vowel of "eye," and a stress peak on it. That's two beats where Japanese wants three. Say ka and i as separate pulses until the three-count sticks, and keep the initial w light — English rounds the lips forward, Japanese just squeezes them.