Figure 4.

Representative rate-place profiles of responses to single and double concurrent vowels. Rate-place profiles of responses to single and double vowels recorded at two sites with BFs of 1200 and 850 Hz (A and B, respectively). Same conventions as in Figure 2. Major peaks corresponding to the first and second formants of the vowels are labeled. Pearson correlation between envelopes of the rate-place profiles (RPPs) at harmonics of the vowels and the corresponding spectral envelopes of the single vowel stimuli (Fig. 1) are shown in C and D for each of the two sites, respectively. For both single and double vowels, rate-place profile envelopes at harmonics of each of the vowels (/a/, blue lines; /i/, red lines) are highly correlated with the spectral envelopes of the matching vowel stimuli, whereas they are poorly correlated with the spectral envelopes of the non-matching vowel stimuli, thereby indicating that A1 responses can be used to identify and discriminate the vowels, both when presented in isolation and concurrently.