Figure 1.

Similarity of spectral envelopes and excitation patterns across stimuli. Frequency spectra of two of the harmonic complexes used in this study. A, B, The f ₀ is (A) 100 Hz or (B) 178 Hz. The f ₀ difference between the tones amounts to 10 semitones, the largest Δf ₀ used. C, The spectra for the 100 Hz (black) and 178 Hz (gray) complex are superimposed. The low-pass noise, apparent in the low-frequency region of each panel, was designed to mask any potential auditory distortion products. The curves plotted above the spectra are excitation patterns in response to harmonic complexes (i.e., relative level of neural activity vs frequency), calculated using a model for the auditory periphery (Glasberg and Moore, 1990). For these curves, the frequency axis indicates tonotopic location along the cochlear partition. The excitation patterns are superimposed in C to illustrate that they are essentially identical.