A contrastive study on the production of double vowels in Mandarin

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Euclidean distance between the primary level learner and the standard speaker_

Female	Initial	Ending	Male	Initial	Ending
[ai]	0.72	1.13	[ai]	1.21	0.44
[ei]	0.92	1.15	[ei]	0.82	0.21
[ao]	0.71	0.39	[ao]	0.94	0.28
[ou]	0.61	0.67	[ou]	1.25	0.72
[ia]	0.68	0.79	[ia]	0.39	0.58
[ie]	0.88	0.01	[ie]	0.31	1.33
[ua]	2.04	1.12	[ua]	1.81	0.62
[uo]	0.42	0.45	[uo]	1.18	1.02
[üe]	0.68	0.76	[üe]	0.25	0.33

Details of subjects’ grouping_

Grouping of subjects	Number of subjects	MHK results	Proficiency
Primary level group	10	Class III B	Beginner
Intermediate level group	10	Grade 3A	Intermediate
Advanced level group	10	Grade 4A	Advanced
Standard group (reference group)	10	–	Standard

Euclidean distance between intermediate learners and standard speakers_

Female	Initial	Ending	Male	Initial	Ending
[ai]	0.83	1.36	[ai]	1.22	1.01
[ei]	0.51	0.61	[ei]	0.87	0.31
[ao]	0.93	0.27	[ao]	0.72	0.83
[ou]	0.52	0.39	[ou]	1.11	0.23
[ia]	1.30	0.63	[ia]	0.26	0.62
[ie]	0.54	0.37	[ie]	0.29	1.46
[ua]	2.96	1.41	[ua]	1.93	0.68
[uo]	0.21	0.62	[uo]	1.21	0.87
[üe]	0.40	0.19	[üe]	0.67	1.07

Euclidean distance between advanced level learners and standard speakers_

Female	Initial	Ending	Male	Initial	Ending
[ai]	1.02	1.52	[ai]	1.27	0.84
[ei]	0.65	0.91	[ei]	0.84	0.85
[ao]	1.01	0.53	[ao]	1.02	1.98
[ou]	0.57	0.64	[ou]	1.09	0.58
[ia]	0.98	0.62	[ia]	0.95	0.99
[ie]	0.52	0.80	[ie]	0.93	0.83
[ua]	2.17	1.35	[ua]	2.56	1.16
[uo]	0.36	0.68	[uo]	1.43	1.27
[üe]	0.38	0.70	[üe]	0.91	0.34