Table 4.

Results of linear mixed-effects regression involving participant group differences in peak frequency (in log Hz). Reference levels are Class I, closed bite, female, /t/, and following /ɑ/.

Predictors	Estimates	SE	Statistic	p
Intercept	8.64	0.03	268.72	< .001
Class II	−0.06	0.04	−1.30	.193
Class III	0.14	0.03	4.14	< .001
AOB	0.19	0.08	2.40	.016
Gender [M]	−0.12	0.04	−2.71	.007
Consonant /s/	0.38	0.03	14.71	< .001
Consonant /ʃ/	−0.43	0.03	−16.61	< .001
Consonant /tʃ/	−0.35	0.03	−13.53	< .001
Following [æ]	0.06	0.02	3.09	.002
Following [i]	0.08	0.02	4.04	< .001
Following [u]	−0.00	0.02	−0.25	.805
Class II × AOB	−0.33	0.10	−3.23	.001
Class III × AOB	−0.19	0.09	−2.18	.029
Class II × gender [M]	−0.05	0.07	−0.70	.485
Class III × gender [M]	−0.14	0.05	−2.50	.013
AOB × gender [M]	−0.33	0.15	−2.23	.026
Class II × consonant /s/	−0.04	0.03	−1.23	.219
Class III × consonant /s/	−0.16	0.02	−6.75	< .001
Class II × consonant /ʃ/	0.06	0.03	2.04	.041
Class III × consonant /ʃ/	−0.15	0.02	−6.47	< .001
Class II × consonant /tʃ/	0.06	0.03	1.92	.054
Class III × consonant /tʃ/	−0.11	0.02	−4.91	< .001
AOB × consonant /s/	−0.23	0.05	−4.24	< .001
AOB × consonant /ʃ/	−0.27	0.05	−5.03	< .001
AOB × consonant /tʃ/	−0.21	0.05	−3.91	< .001
Gender [M] × consonant /s/	−0.18	0.03	−5.98	< .001
Gender [M] × consonant /ʃ/	−0.12	0.03	−4.23	< .001
Gender [M] × consonant /tʃ/	−0.08	0.03	−2.55	.011
(Class II × AOB) × gender [M]	0.47	0.18	2.62	.009
(Class III × AOB) × gender [M]	0.27	0.16	1.71	.087
(Class II × AOB) × consonant /s/	0.35	0.07	5.00	< .001
(Class III × AOB) × consonant /s/	0.19	0.06	3.23	.001
(Class II × AOB) × consonant /ʃ/	0.31	0.07	4.48	< .001
(Class III × AOB) × consonant /ʃ/	0.28	0.06	4.62	< .001
(Class II × AOB) × consonant /tʃ/	0.23	0.07	3.27	.001
(Class III × AOB) × consonant /tʃ/	0.14	0.06	2.27	.023
(Class II × gender [M]) × consonant /s/	0.12	0.05	2.69	.007
(Class III × gender [M]) × consonant /s/	0.16	0.04	4.36	< .001
(Class II × gender [M]) × consonant /ʃ/	0.04	0.05	0.99	.320
(Class III × gender [M]) × consonant /ʃ/	0.16	0.04	4.32	< .001
(Class II × gender [M]) × consonant /tʃ/	0.12	0.05	2.59	.010
(Class III × gender [M]) × consonant /tʃ/	0.13	0.04	3.63	< .001
(AOB × gender [M]) × consonant /s/	0.25	0.10	2.46	.014
(AOB × gender [M]) × consonant /ʃ/	0.56	0.10	5.53	< .001
(AOB × gender [M]) × consonant /tʃ/	0.41	0.10	3.97	< .001
(Class II × AOB × gender [M]) × consonant /s/	−0.32	0.12	−2.63	.009
(Class III × AOB × gender [M]) × consonant /s/	−0.25	0.11	−2.29	.022
(Class II × AOB × gender [M]) × consonant /ʃ/	−0.60	0.12	−4.95	< .001
(Class III × AOB × gender [M]) × consonant /ʃ/	−0.49	0.11	−4.43	< .001
(Class II × AOB × gender [M]) × consonant /tʃ/	−0.45	0.12	−3.68	< .001
(Class III × AOB × gender [M]) × consonant /tʃ/	−0.26	0.11	−2.32	.020
Random effects
σ2	0.07
τ00 speaker	0.02
τ00 word	0.00
ICC	.24
N word	16
N speaker	284
Observations	12,994
Marginal R2/conditional R2	.555/.661

Note. Values in bold are significant by p < .05 convention. SE = standard error; AOB = anterior open bite; ICC = intraclass correlation coefficient.