auditory images in Figure 3: (a) CPH, (b) AAMP(9), (c) AAMP(18), (d) APH(90), and (f) AAMP(9)/ APH(90). Tone height increases when the similarity between the 8- and 4-ms patterns increases.

Now consider how the tone-height values would change as the odd harmonics are attenuated, or phase shifted, or both. The attenuation of the odd harmonics rapidly removes them from the 8-ms excitation pattern as shown by the patterns for AAMP(9) and AAMP(18) on the lefthand sides of Figures 4b and 4c. At the same time, however, it removes the odd harmonics from later patterns in the sequence and so the odd harmonics rapidly drop out of the calculation altogether. The attenuation increases the activity of the even harmonics in the 4-ms excitation patterns as shown on the righthand sides of the same subfigures. This gradually shifts the maximum-level-difference of more and more harmonics from the 8-ms/ 4-ms pair of patterns to the 4-ms/2-ms pair of patterns, and so gradually raises the overall tone-height value from octave 3 to octave 4.