How Wide Is Wide Enough? Singing, Resonance, and Vowel Shaping Explained

If you’ve sung in choirs or taken lessons, you’ve probably heard the phrase:“Open your mouth wider.”

This instruction can be useful at times, but it doesn’t tell the whole story. Great singing isn’t about how wide you open—it’s about how you shape your vocal tract to bring out resonance, clarity, and expression.

What Resonance Really Means

When you sing, two things happen at once:

Source: Your vocal folds vibrate, creating a pitch with a whole spectrum of overtones.
Filter: Your vocal tract (throat, mouth, lips) shapes and amplifies parts of that spectrum.

This interaction—often called the source-filter model—is what creates resonance. So the question isn’t simply “how wide is my mouth?” but rather “how is my whole vocal tract shaping the sound?”

Where Singers Actually Create Space

Singers often think of “space” as jaw opening, but resonance depends on several areas working in balance:

Jaw: Should move freely but naturally. A moderate drop allows vowels to resonate clearly. Forcing it wider often destabilizes pitch and vowel purity.

👉 Exercise: Jaw Freedom Check

Sing on “ah” at a comfortable pitch.
Gently wiggle your jaw while singing — just enough to see if it’s locked.
Then sing again, letting the jaw release naturally.
✨ Goal: notice how resonance clears when the jaw is free, not forced.
Lips: Adjust to refine vowels. Subtle rounding or spreading can dramatically change resonance, especially on higher notes.

👉 Exercise: Lip Shape Resonance Shift

On a mid-range note, sing “ah.”
Very slightly round your lips forward, then gently relax them back.
Listen to how the brightness and depth shift, even though the vowel stays similar.
✨ Goal: discover how lip adjustments change resonance without needing “wider.”
Tongue & Pharynx: The tongue’s position controls much of vowel quality. Too much retraction or pharyngeal widening can make sound muffled, but gentle shaping adds richness.
Soft Palate: Lifts to prevent nasal leakage and allow full oral resonance. The goal is flexible movement, not a rigid “ceiling.”

The key: resonance isn’t about maximum space in one place. It’s about balanced shaping across the tract.

Singing Higher: Do We Just “Add Space”?

Another common idea is: “As you go higher, just open more.”

There’s truth here—higher pitches often require subtle vowel adjustments—but simply “adding space” isn’t the solution.

In classical technique (bel canto, choral, operatic), singers use vowel modification (Burton Coffin’s Chromatic Vowel Chart illustrates this beautifully). As pitch rises, vowels are adjusted so resonance aligns with the overtone series, keeping the tone full and ringing.
In pop and contemporary singing, vowels remain closer to everyday speech, but subtle shifts still occur. Belt, mix, and twang all rely on resonance tuning—just expressed differently than in opera.

So across styles, the principle is the same: we adapt vowels to the pitch, not just open wider.

👉 Exercise: Vowel Alignment Explorer

Choose a simple 3–5 note scale.
Sing it first on “ee.”
As you ascend, allow the vowel to adapt: let it feel taller in the throat, sometimes closer to “ih” or a lightly rounded “ih/eh,” depending on your voice.
Try the same on “ah” or “oo,” noticing how each vowel finds its own “sweet spot.”
✨ Goal: experience how vowels naturally adjust with pitch. Not all open more, not all narrow — each finds its own resonance balance.

The Ring of Resonance

Listeners often describe great singing as having “ring,” “shine,” or “cut.” Acoustically, this comes from a cluster of amplified overtones called the singer’s formant, usually between 2.5–3 kHz.

This brilliance doesn’t happen by opening wider. It happens when the vocal tract is shaped to let harmonics align efficiently with resonant frequencies. In other words, the voice carries when resonance is tuned, not when the jaw is stretched.

👉 Exercise: Resonance Matching Drill

Sing a comfortable pitch on “oo.”
Then sing the same pitch on “oh,” then “ah.”
Notice which vowel feels easiest, clearest, or “rings” most in your voice.
Repeat the sequence higher and lower in your range.
✨ Goal: train your ear and body to recognize where resonance feels most efficient on each vowel, instead of forcing “open wider.”

Practical Guidelines for Singers

When you’re working on resonance, here are a few things to keep in mind:

Allow, don’t force, jaw movement. Openness should feel free, not strained.
Listen for vowel clarity. Subtle lip or tongue adjustments can make vowels “ring” without more jaw space.
Adapt vowels as you ascend. Higher notes often need slight rounding or narrowing to stay resonant.
Think acoustics, not mechanics. The goal is efficient sound, not just bigger movement.
Use resonance sensations as feedback. The “buzz” or “ring” you feel is a sign of efficiency—not the end goal itself.

👉 Exercise: Gentle Vowel Bridge

Sing on “oo” at a mid pitch, then gradually allow it to morph toward “ah” while holding the same note.
Focus on a smooth transition rather than a sudden switch.
✨ Goal: feel how small vowel shape shifts (jaw, lips, tongue, throat) change resonance balance — and that there isn’t one “right” width.

Classical and Pop: Two Roads, Same Principles

Classical singing emphasizes systematic vowel modification, resonance balance, and sustained tone for projection in large halls.
Pop/contemporary singing values speech-like clarity and stylistic authenticity, using subtler shaping to support flexibility, belt, and mix.

Though the styles differ, the principle remains: resonance matters in every genre.

Final Thoughts

“Open your mouth wider” may sometimes help, but it isn’t the full answer. Singing well comes from understanding how to shape your entire vocal tract—jaw, lips, tongue, pharynx, and soft palate—to let your voice resonate freely across your range.

And that’s where skilled guidance makes the difference. Instead of guessing how much to open or which vowel to use, you can learn strategies tailored to your voice and your style.

🎤 Ready to Sing with True Resonance?

At Ted’s Voice Academy, I help singers discover the resonance strategies that unlock consistency, projection, and artistry. Whether you sing opera, pop, or musical theatre, you can learn to shape your sound with confidence.

👉 Book a lesson today, and experience what your voice is truly capable of.

Should You “Open Your Mouth Wider” When Singing? The Real Story