Diphthong · o It starts at /o/: tongue body mid-high and back, lips already rounded, then glides to a higher, tighter /ʊ/. The drawing is the start — dropping the second half is the most common error.
Three steps to /oʊ/
Start rounded, then tighten once.
Round the lips, raise the tongue back
The /o/ start is already rounded, with the tongue body high-mid and back. Contrast /ɔ/: that one is rounded with the jaw open; /o/ is much closer.
Glide into a tighter /ʊ/
Tongue up a little, lips tighter a little. This is not two syllables — it is one closing movement of about 150–250 ms.
Self-check: the ending must close
Say go, then a flat monophthong /o/. go tightens at the end. A hand under the chin should feel a slight lift.
Articulation (side view)
One speaker, one instant: tongue position and lip shape only. The amber circle marks what to look at; the caption says how it differs from the sound it is usually confused with.
Spelling: o, oa and ow
Open-syllable o is /oʊ/; oa and ow often are. oa is the most reliable.
o + consonant + e, or final o: go, home, note, hope. Final o is usually /oʊ/ (go, so, no).
The most stable mapping of the four.
★ Two readings: know / show / low are /oʊ/; now / how / down are /aʊ/. Per word — the biggest spelling trap here.
ough has at least six readings: though /oʊ/, through /uː/, thought /ɔ/, cough /f/, rough /ʌ/, bough /aʊ/.
Why learners replace /oʊ/
The nearest L1 vowel is a monophthong; /oʊ/ needs two stages.
Reduced to a monophthong
go → /ɡo/, home → /hom/. It sounds «close enough», but the missing closing movement is audible to native listeners.
Compare the end of every clip on this page: the lips tighten again in the second half.
Start not rounded enough
Lips only partly closed, so the result drifts toward /ʌ/ or /ɔ/.
The start is /o/: compare this drawing with the /ɔ/ page.
ow read as /aʊ/ everywhere
Having learned down = /aʊ/, know becomes /knaʊ/ and show becomes /ʃaʊ/.
Per word: know, show, low, slow, grow, throw, snow are all /oʊ/.
Word list
27 words grouped by where the sound sits in the word. Click a word to hear it. These are recorded as separate words, not cut out of the sentences above — a word cut from a sentence carries its neighbours' transitions and always sounds muddier. All three groups use the same speaker, so what changes between them is position, not voice.
Word-initial9
Word-medial9
Word-final9
Three groups of nine. The final group (go, so, no, low, slow, grow, throw, snow, below) is uniformly /oʊ/ — final o and ow both read /oʊ/.
Corpus and acoustic measurements
Click any word in a sentence to play from that word. The pale band over the waveform marks the measured boundary of the target word.
Per-token data
Every number below is measured directly from the audio, not hand-annotated.
| Token | Accent | Sex | Target | Word length | oʊ duration | F0 | Pitch range | HNR |
|---|
Where the numbers come from
Every figure on this page can be recomputed from the description below.
Corpus: 12 English sentences synthesised with four American voices (two male, two female), each containing one target word, covering initial, medial and final positions. Audio is 22.05 kHz mono 64 kbps; each clip runs from 1.2 s before to 1.5 s after the target word.
Word boundaries: taken from the engine's word-level timestamps (WordBoundary) and corrected for the fixed offset between the engine timeline and the audio start (estimated per item). The target word is shaded in the waveform.
Phoneme boundaries: measured by forced alignment with the MMS_FA acoustic model. Each character's aligned frame range is kept, then a dynamic program maps the character sequence onto the phoneme sequence (th→θ, ng→ŋ, ck→k). Boundaries fall in the middle of the transition between characters; within-word coverage is 100%. Time precision is the model frame length, 20 ms, and boundaries are taken at midpoints, so effective resolution is about 10 ms.
Pitch: Praat's autocorrelation (to_pitch), 10 ms frame step, search range narrowed to the speaker's estimated range, octave errors removed. «Pitch range» is max minus min F0 within the word.
Why there are no paired differences here: this is a single-phoneme page. Eight other pages are contrast pages (θ/ð, l/r/n, vowel length) where the numbers come from paired words read by one speaker. A single-phoneme page has nothing to compare against — pairing it with a neighbour would measure that neighbour, which belongs to a different page.