Table 1. Matrix of associations between synthesized sounds and vowels.

	A	E	I	O	U
A	20	0	0	0	0
E	0	17	2	1	0
I	0	2	16	0	2
O	2	0	0	18	0
U	0	0	0	4	16

Associations between vowels (first row) and synthesized sounds (first column) for 20 participants. The sounds were synthesized using the anatomical parameters of table 2 for the 5 Spanish vowels, as displayed in figure 2, and fixed source parameters (see Methods). The incorrectly associated audio files correspond mainly to neighboring vowels in the space (see figure 2).