Table 2.
Within-subject differences between mothers' ID and AD speech.
| Predictors | ID |
AD |
Mean difference |
95% CI of the mean difference |
t(df) | p | |||
|---|---|---|---|---|---|---|---|---|---|
| M | SE | M | SE | M | SE | [Min, Max ] | |||
| Lexical | t(35) | ||||||||
| Lexical quantity | 64.3 | 2.7 | 104.0 | 4.9 | −39.7 | 3.9 | [−47.7, −31.7] | −10.1 | < .001 |
| Lexical diversity | 0.33 | 0.01 | 0.51 | 0.01 | −0.18 | 0.02 | [−0.21, −0.15] | −12.1 | < .001 |
| Suprasegmental | t(35) | ||||||||
| Speech rate (syllables/s) | 3.8 | 0.12 | 4.4 | 0.09 | −0.58 | 0.12 | [−0.79, −0.36] | −5.5 | < .001 |
| Median F0 (Hz) | 272.5 | 6.5 | 187.4 | 3.9 | 85.1 | 5.3 | [74.3, 95.8] | 16.1 | < .001 |
| F0 variability (Hz) | 127.5 | 6.5 | 35.3 | 2.0 | 92.2 | 6.7 | [78.6, 105.8] | 13.8 | < .001 |
| Segmental | t(34) | ||||||||
| Vowel space area (mels) | 71,317.5 | 5,396.7 | 62,924.7 | 3,945.5 | 8,392.8 | 6,023.7 | [−3,848.8, 20,634.4] | 1.4 | .173 |
| Vowel dispersion (mels) | 342.5 | 5.7 | 328.8 | 5.3 | 13.7 | 7.3 | [−1.0, 28.4] | 1.9 | .068 |
Note. ID = infant-directed; AD = adult-directed; CI = confidence interval.