Say "teeny." Now say "huge." Small things in English tend to get thin, high sounds, like teeny, itsy-bitsy, mini, and little. Big things tend to get wide, open ones, like huge, large, vast, and humongous. That is not a coincidence. There is a real pattern buried in the sounds of the language, and once you hear it, English pronunciation starts to feel less like a random list of noises and more like a system you can reason about.
The linguist Steven Pinker describes this pattern in his book The Language Instinct. It is called phonetic symbolism, and it is one of the most charming facts about how speech works. It is also a useful way in to the part of TOEFL Speaking that trips up a lot of learners: pronunciation and being understood.
Quick answer
Phonetic symbolism is the tendency for the sound of a word to hint at its meaning. In English, sounds made with the tongue high and toward the front of the mouth, like the "ee" in "teeny," are linked to small, light, or near things. Sounds made with the tongue low and toward the back, like the "ah" in "large," are linked to big, heavy, or far things. The reason is physical: a small mouth space makes a high, thin sound, and a large mouth space makes a low, full one. Understanding that speech is shaped by the physical position of your tongue and lips is exactly what makes pronunciation learnable.
Your mouth is a musical instrument
Here is the mechanism, and it is the useful part. When you make a vowel, your tongue and lips change the size and shape of the space the sound travels through. A smaller space resonates at a higher pitch, and a larger space resonates at a lower one. It is the same reason a small speaker, a tweeter, handles the high notes and a big speaker, a woofer, handles the low ones.
So when your tongue is high and forward, the space in front of it is small, and you get a high, thin vowel like "ee." When your tongue drops low and pulls back, the space is large, and you get a deep, open vowel like the "a" in "father." Your brain, hearing these sizes, links the small, high sound to small things and the big, low sound to big things. Mice squeak. Elephants roar. Even across languages the effect leaks through: English speakers guessing at foreign words tend to feel that a high "ee" word is the light one and a low "oo" or "ah" word is the heavy one, at a rate a little better than chance.
Small sounds and big sounds
Once you know the pattern, you start seeing it everywhere. Here is the small end against the big end.
The words at the small end are made with the tongue high and forward. The words at the big end open the mouth up and pull the tongue back. Say them and feel it.
The ping-pong rule: ablaut reduplication
There is a second sound pattern here, and it is worth keeping separate from the size effect above. When English repeats a word with a vowel change, the vowels follow a set order: roughly I before A before O. Linguists call it ablaut reduplication. It is why you say tick-tock and not tock-tick, and flip-flop and not flop-flip. You say them in one order and never the other.
English loves these paired words in general, from razzle-dazzle and super-duper to helter-skelter, hocus-pocus, mumbo-jumbo, namby-pamby, and roly-poly. But when the pair differs by its vowel, the high front one leads every time.
A related but different pattern, this one driven by meaning rather than by sound alone, shows up in words tied to the speaker. The "close to me" word tends to come first: here and there, this and that, now and then, me and you. This is the sound-symbolism side that Pinker discusses: the mouth shape for "me, here, now" is high and front, and that high front sound tends to lead. Nobody fully knows why English lines these up so reliably, but the pattern is remarkably consistent.
Sound is physical, and that is good news for your English
Here is why this matters for a TOEFL Speaking test taker, and I want to be honest about it. Knowing phonetic symbolism will not raise your score by itself. It is not a hack. What it does is change how you think about pronunciation.
Most learners treat English sounds as a mysterious list they either can or cannot produce. Phonetic symbolism shows the opposite. Every sound is the predictable result of where you put your tongue and lips. "Sheep" has your tongue high and forward; for "ship," it relaxes and moves slightly lower and back. Those two vowels differ in position, in muscular tension, and often in length. That is not magic. It is a set of physical adjustments, and it is completely learnable.
That reframing is the point. Pronunciation is a set of physical positions you can practice, not a talent you were born with or without. And on the TOEFL, being clearly understood, what the scoring calls intelligibility, is one of the things that matters most.
A simple map of the vowels
Here is the small-to-big pattern laid out. It is a rough map, not a rulebook, but it shows the logic.
Notice that "ship" and "sheep" sit right next to each other on this map. That closeness is exactly why they are so easy to confuse, and why fixing them is about a small, deliberate change in tongue position, not about starting over.
How to use this
Do not try to memorize the pattern. Use it as a mindset. The next time a sound feels impossible, stop treating it as a mystery and ask a physical question: where is my tongue, and where does it need to be? For "sheep," raise and tighten the tongue for a longer, higher "ee." For "ship," relax it slightly. Feel the difference, then drill the pair. When you approach pronunciation as physical positions, the sounds that break your meaning become a short, fixable list.
See where your sounds land
The fastest way to find the sounds costing you clarity is to hear yourself. Take a free practice test on My Speaking Score, record an interview answer, and listen for the words where meaning could slip. Those spots point to the specific tongue positions worth drilling, and now you have a way to think about each one.
FAQ
What is phonetic symbolism?It is the tendency for a word's sound to reflect its meaning. In English, high front vowels like "ee" are linked to small or near things, and low back vowels like "ah" to big or far things, because of the physical size of the mouth space that makes them.
Is phonetic symbolism real or a coincidence?It is a real, documented tendency, described by linguists including Steven Pinker. It is a strong pattern rather than an absolute rule, and it appears across many languages.
Does knowing this improve my TOEFL Speaking score?Not on its own. It is not a shortcut. Its value is in reframing pronunciation as physical tongue and lip positions you can learn, which makes fixing the sounds that hurt your clarity far less intimidating.
Why is it always "ping-pong" and never "pong-ping"?English strongly prefers to put the high, front vowel first in paired words like ping-pong, tick-tock, and criss-cross. The reason is not fully understood, but the pattern is very consistent, as Pinker notes.
How does this help with sounds like "ship" and "sheep"?Those two vowels sit very close together in the mouth, which is why they are easy to confuse. Seeing them as a small difference in tongue position, rather than two unrelated sounds, makes the fix concrete and quick.
The takeaway
English hides a quiet logic in its sounds. Small, near things get high, thin vowels; big, far things get low, open ones; and paired words run high-vowel-first, from ping-pong to this and that, all because your mouth is shaped like an instrument. That is a delightful fact on its own, and it carries a practical lesson for anyone preparing for TOEFL Speaking: pronunciation is physical, and physical things can be learned. You do not have to be born with the right sounds. You just have to know where to put your tongue.
Source and further reading: Steven Pinker, The Language Instinct: How the Mind Creates Language. Overview and quotes: https://www.goodreads.com/book/show/5755.The_Language_Instinct