Vowel Articulation Trainer

Articulators

Tongue height Mid

Tongue advancement Central

Lip rounding 0%

Target vowel

match to target

Formants

F1 (height)

–

F2 (backness)

–

F2 high F2 low F1 low F1 high

How it works

Speech is produced by a source (vocal-fold vibration) filtered by the resonant cavities of the vocal tract — the source-filter theory of speech production. As the tongue, jaw and lips change the tract's shape, they shift its resonant frequencies, called formants (F1, F2, F3…). Vowels are identified almost entirely by the frequencies of the first two formants.

F1 ≈ 800 − 550·height   (Hz)   — tongue raised → lower F1
F2 ≈ 900 + 1400·front − 500·round (Hz) — tongue fronted → higher F2, rounding → lower F2

Raising the tongue narrows the tract higher up and shrinks the main oral cavity, which lowers F1. Moving the constriction forward shortens the back (pharyngeal) cavity relative to the front one, which raises F2. Rounding the lips lengthens the tube and narrows its opening, which lowers all formants, most noticeably F2.

Tongue height / advancement / lip rounding — reshape the 3D vocal tract and recompute F1/F2 in real time.
Target vowel buttons — set a green ring on the F1–F2 chart for one of the English monophthongs; drag the sliders until your orange dot lands inside it.
Match % — how close your formants are to the target, in the same normalized F1–F2 distance metric clinicians use to score articulation-therapy exercises.

Real-world relevance: this is a simplified version of visual acoustic biofeedback, a technique speech-language pathologists use with real-time formant/spectrogram displays to treat vowel distortions in apraxia, dysarthria, hearing-impairment and accent-modification therapy — letting a patient *see* the target they are trying to hit, not just hear it.

Vocal tract (throat → lips) Tongue constriction

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