Infant-directed speech: Final syllable lengthening and rate of speech
Bibliographic record
Abstract
Speech rate has been reported to be slower in infant-directed speech (IDS) than in adult-directed speech (ADS). Studies have also found phrase-final lengthening to be more exaggerated in IDS compared with ADS. In our study we asked whether the observed overall slower rate of IDS is due to exaggerated utterance-final syllable lengthening. Two mothers of preverbal English-learning infants each participated in two recording sessions, one with her child, and another with an adult friend. The results showed an overall slower rate in IDS compared to ADS. However, when utterance-final syllables were excluded from the calculation, the speech rate in IDS and ADS did not differ significantly. The duration of utterance-final syllables differed significantly for IDS versus ADS. Thus, the overall slower rate of IDS was due to the extra-long final syllable occurring in relatively short utterances. The comparable pre-final speech rate for IDS and ADS further accentuates the final syllable lengthening in IDS. As utterances in IDS are typically phrases or clauses, the particularly strong final-lengthening cue could potentially facilitate infants’ segmentation of these syntactic units. These findings are consistent with the existing evidence that pre-boundary lengthening is important in the processing of major syntactic units in English-learning infants.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".