Eight rounds is enough to show you whether your ear splits these two apart yet. It does not tell you why they collapse into one sound in the first place, and that part is where the fix lives.
The Difference Isn't Really Length
Textbooks call these "short i" and "long e," so most learners listen for duration. Native speakers mostly don't. The bigger difference is the shape of your mouth. For sheep, the tongue sits high and pushed forward, the lips pull slightly wide, and everything is tight. For ship, the tongue drops a little and slides back, and the whole thing relaxes. Two different shapes, two different sounds. The length difference is mostly a side effect of that.
Why Counting Length Will Trick You
English vowels stretch depending on what comes after them. The vowel in bead is clearly longer than the vowel in beat, even though it is the same vowel both times. That works in reverse too: the "short" vowel in his can run longer than the "long" vowel in peace. So if duration is your only clue, English hands you the wrong answer on a regular basis. You need the mouth shape, not the stopwatch.
Where It Shows Up Away From This Test
This one pair gets used as the example, but the same vowel runs through a lot of everyday words:
live / leave
"I live in Seoul" and "I leave in Seoul" are one relaxed vowel apart.
sit / seat
Common in restaurants and offices, where either word would make sense.
fit / feet
Clothing shops, shoe sizes, gym conversations.
chip / cheap
"That's chip" and "that's cheap" land very differently.
still / steel
Turns up more at work than you'd expect.
is / ease
Both unstressed and fast, so context has to carry it.
Context rescues most of these. The ones that actually hurt are where both options fit the sentence — and those are exactly the moments a subtitle would have quietly answered for you before your ear had to.
Why Your Ear Merged Them
Korean, Japanese and Spanish do not mark vowel length the way English does. A five-vowel system has no slot for a short i sitting next to a long e, so your ear is not learning a new word here. It is building a new category from nothing, which is a slower process than vocabulary and explains why exposure alone often fails to fix it. Knowing that changes what practice should look like: short, repeated, deliberate comparison beats hours of passive listening.
Where This Vowel Turns Up Again
- full / fool
The same tight-mouth versus relaxed-mouth split, moved to a different vowel.
- bad / bat
Hear the stretching effect on its own — same vowel, length changed only by the consonant after it.