Appendix 1. Results of model (1) and (2)

Predictors	F1			F2
	Estimates	CI	p-value	Estimates	CI	p-value
(Intercept)	905.52	870.22–940.83	<0.001	1,368.40	1,270.45–1,466.35	<0.001
NK	19.26	–22.74–61.27	0.369	123.67	–3.42–250.77	0.056
[i]	–505.83	–542.10– –469.55	<0.001	506.86	363.23–650.49	<0.001
[e]	–288.91	–324.94– –252.89	<0.001	744.31	604.06–884.57	<0.001
[æ]	–293.43	–332.81– –254.04	<0.001	710.42	572.72–848.12	<0.001
[ʌ]	–259.06	–297.70– –220.43	<0.001	–354.58	–475.40– –233.75	<0.001
[o]	–458.29	–497.91– –418.68	<0.001	–472.50	–593.28– –351.71	<0.001
[ɯ]	–447.09	–484.59– –409.59	<0.001	102.22	–19.38–223.83	0.099
[u]	–480.71	–518.52– –442.90	<0.001	–342.18	–466.13– –218.23	<0.001
Conversation	–171.49	–205.71– –137.27	<0.001	–1.76	–104.72–101.20	0.973
NK×[i]	–2.93	–54.82–48.95	0.912	–166.00	–370.57–38.57	0.112
NK×[e]	–65.93	–117.64– –14.22	0.012	–273.86	–474.07––73.65	0.007
NK×[æ]	40.73	–15.30–96.76	0.154	–261.86	–457.58––66.14	0.009
NK×[ʌ]	–71.07	–126.23– –15.92	0.012	–31.79	–204.45–140.87	0.718
NK×[o]	75.55	19.11–132.00	0.009	–34.58	–206.89–137.73	0.694
NK×[ɯ]	–20.94	–74.52–32.63	0.444	–125.54	–299.29–48.20	0.157
NK×[u]	–2.76	–56.85–51.34	0.920	–81.20	–258.49–96.10	0.369
NK×Conversation	27.69	–18.85–74.23	0.244	–31.99	–171.54–107.57	0.653
[i]×Conversation	244.68	205.15–284.20	<0.001	4.14	–124.56–132.84	0.950
[e]×Conversation	119.86	78.94–160.78	<0.001	–153.08	–287.84– –18.32	0.026
[æ]×Conversation	146.67	107.52–185.81	<0.001	–204.71	–332.05– –77.36	0.002
[ʌ]×Conversation	81.35	42.44–120.27	<0.001	27.75	–98.51–154.01	0.667
[o]×Conversation	201.01	162.99–239.04	<0.001	179.86	56.37–303.35	0.004
[ɯ]×Conversation	213.57	175.44–251.69	<0.001	–16.73	–140.58–107.12	0.791
[u]×Conversation	210.15	171.65–248.64	<0.001	230.02	104.93–355.10	<0.001
(NK×[i])×Conversation	–23.17	–79.28–32.94	0.418	75.98	–109.78–261.75	0.423
(NK×[e])×Conversation	34.77	–21.76–91.31	0.228	148.44	–37.44–334.31	0.118
(NK×[æ])×Conversation	–35.82	–90.90–19.26	0.202	193.16	14.07–372.25	0.035
(NK×[ʌ])×Conversation	36.68	–17.87–91.23	0.188	86.59	–90.54–263.73	0.338
(NK×[o])×Conversation	–49.84	–103.76–4.07	0.070	–11.24	–186.40–163.91	0.900
(NK×[ɯ])×Conversation	3.02	–50.97–57.00	0.913	61.67	–113.75–237.09	0.491
(NK×[u])×Conversation	–13.71	–68.15–40.72	0.621	21.46	–155.43–198.35	0.812