Lexical stress

Lexical stress analysis shows how strongly each syllable was stressed and, when available, which syllable is expected to carry primary stress. The preview is returned automatically for supported requests; no additional request field is required.

Response location

Stress information appears inside:

word_groups[].syllables[].stress

For example:

{
  "text": "banana",
  "syllables": [
    {
      "index": 0,
      "text": "ba",
      "stress": {
        "score": 0.08,
        "expected": false
      }
    },
    {
      "index": 1,
      "text": "na",
      "stress": {
        "score": 0.87,
        "expected": true
      }
    },
    {
      "index": 2,
      "text": "na",
      "stress": {
        "score": 0.12,
        "expected": false
      }
    }
  ]
}

Fields

Field	Type	Meaning
`score`	number	Detected stress strength for this syllable, from `0` to `1`. Higher values indicate stronger evidence of lexical stress.
`expected`	boolean	Whether this is the expected primary-stress syllable. Included only when an expected stress pattern is available.

A score near 0 indicates little detected evidence of lexical stress, while a score near 1 indicates strong evidence. Values between them represent increasing detected stress strength. Each scoreable syllable receives its own score and is evaluated independently, so scores do not need to sum to 1.

Availability

The preview currently supports English (en). Additional languages are under evaluation. The stress object is optional and may be omitted when unavailable. When the expected pattern is unavailable, score can still be returned without expected.

Recommended integration

For every syllable with stress metadata, show the score and highlight expected: true when present:

for (const word of response.word_groups ?? []) {
  for (const syllable of word.syllables ?? []) {
    const stress = syllable.stress;

    if (!stress) continue;

    renderSyllableStress({
      text: syllable.text,
      scorePercent: Math.round(stress.score * 100),
      expected: stress.expected === true,
    });
  }
}

Monosyllabic words

A one-syllable word can still receive a stress score representing its detected stress strength. Stress-placement feedback applies only to multisyllabic words.

Lexical stress vs prosody contours

Lexical stress and the optional prosody contour answer different questions:

Feature	Response field	Interpretation
Lexical stress	`syllables[].stress.score`	Syllable-level evidence of word stress
Prosody contour	`word_groups[].prosody.stress_contour`	Frame-level relative emphasis across a word

The prosody contour requires enable_prosody_contours=true. Lexical stress is returned automatically when supported.

Getting started

Reference

Preview

Response location

Fields

Availability

Recommended integration

Monosyllabic words

Lexical stress vs prosody contours

​Response location

​Fields

​Availability

​Recommended integration

​Monosyllabic words

​Lexical stress vs prosody contours

Response location

Fields

Availability

Recommended integration

Monosyllabic words

Lexical stress vs prosody contours