A few days ago on the blog, we discussed the importance of physically moving your mouth when making American English sounds, specifically your tongue position, lip shaping, jaw position, and muscle tension.
In this post, we’re going take another look at this topic, with a particular focus on opening up your mouth and jaw to make individual sounds more distinct and differentiated.
When Different Vowels Start Sounding the Same
When you’re not making individual sounds in English properly, it’s often due to what speech coaches sometimes call vowel compression. The individual vowels are technically present, but they aren’t given enough physical space to become clearly distinct.
Think about it this way: imagine trying to paint with five colors, but all of them are only tiny variations of gray. The colors are there, but the differences between them are difficult to see.
The same thing can happen with your English speech if you don’t open up your mouth enough for certain sounds. When lip movement is minimal and jaw movement is restricted, vowels that should sound very different begin drifting toward the same middle position.
Words such as bed, bad, bud, and bod can start sounding close to one another due to a clear lack of vowel differentiation. This isn’t because the speaker doesn’t know the difference, but because the mouth isn’t fully expressing the difference.
The Hidden Problem: Limited Articulatory Range
The problem stems from what speech scientists call the articulatory range, which simply means how much your speech muscles move when producing sounds. English vowels require significant movement from:
- The jaw
- The lips
- The tongue
American English, in particular, tends to use:
- Noticeable jaw opening on low vowels (such as the /æ/ in bat and /ɑ/ in hot)
- Active lip rounding on back vowels (such as /oʊ/ in go and /u/ in do)
- Clear tongue movement between front and back vowel positions
When these movements become small or restricted, vowel distinctions shrink and everything starts occupying the same acoustic neighborhood. The result is that specific sounds, or even your speech in general, can sound compressed, mumbled, or indistinct.
Why This Happens
What’s important to recognize is that even advanced speakers can speak with compressed vowels. This is frequently because they tend to speak with the same articulatory range as in their native language, which is often quite limited compared to the range in English. As one client told me, “I can mumble in my native Russian and be completely understood!”
The truth is that you may simply have to open up your mouth more to make certain sounds in English than you do in your native language.
Another common issue for speakers is an unconscious tensing of the jaw and throat while speaking, especially when they get a bit nervous or anxious. Keeping your jaw and throat relaxed when you speak will help you open up more and increase your articulatory range in English.
A Simple Test
This is an exercise I have done with my clients, but you can do it on your own too. Here’s what you have to do: record yourself reading a paragraph on video, then mute the sound and watch the recording.
Ask yourself:
- Do my lips visibly change shape?
- Does my jaw open and close noticeably?
- Can I see clear movement between vowels?
- Do I look expressive or almost frozen?
If you watch and judge yourself objectively, you might be surprised by what you discover. Sometimes the speech feels active to you from the inside, but looks almost motionless from the outside.
The Exaggerated Vowel Circle
Voice coaches often use warm-ups that intentionally increase articulatory range. One of the simplest is the exaggerated vowel circle.
Move slowly through these vowels:
- /iː/ as in see
- /ɑː/ as in father
- /uː/ as in food
- /ɛ/ as in bed
- /ʌ/ as in cup
For each vowel:
- Maximize lip movement.
- Maximize jaw movement.
- Hold the sound for a second or two.
- Focus on making each shape feel completely different.
The goal isn’t to speak this way in conversation, but to activate your facial muscles and remind your muscles how much range is available to you. Think of it like stretching warm-up exercises before a workout, except for your speech instead of your body.
What Good Articulation Looks Like
Good articulation does not mean: overacting, exaggerating every syllable, or speaking unnaturally slowly. We also don’t want to turn you into a version of yourself that feels “fake” or inauthentic!
Good articulation means allowing each vowel to reach the physical position it requires. For example, the vowel in beat needs a very different tongue and lip position than the vowel in boot. And the vowel in bad requires far more jaw opening than the vowel in bid.
If those positions aren’t physically distinct, the listener hears less contrast, which can make the sound “clipped,” incomplete, or too similar to another sound. Needless to say, all of these have a negative effect on your English accent.
Why Expressive Articulation Matters
One reason American English can sound so dynamic is that speakers often use a fairly wide articulatory range: the jaw moves, the lips may round, and the tongue travels. These movements create clear acoustic differences between sounds.
When you reduce those movements too much, the speech may sound flatter, even when the pronunciation is technically correct.
If people describe your English as mumbled, compressed, or difficult to understand, try focusing less on individual sounds and more on the physical space you’re giving those sounds.