Several magnitude and timing features of the responses of chinchilla auditory-nerve fibers (ANFs) are correlated and undergo transitions in cochlear regions with the same characteristic frequencies (CFs), 1 and 3–4 kHz. At the region with CF of 1 kHz, transitions occur in the direction of the asymmetry of frequency-threshold tuning curves, FTCs (

Temchin et al., 2008), the asymmetrical level-dependent shifts of rate-vs.-frequency curves (

Temchin and Ruggero, 2010), the curvature of phase-vs.-frequency curves (

Temchin and Ruggero, 2010), and the direction of the onset frequency glides in impulse responses (

Recio-Spinoso et al., 2005;

Temchin et al., 2005). At the cochlear region with CFs of 3–4 kHz, transitions occur for the shapes of FTCs, including the slopes of their lower limbs and the associated tip-to-tail ratios, and of phase-frequency curves (

Temchin et al., 2008). The present investigation explores whether linear transfer functions derived from ANF FTCs can predict the timing features of cochlear responses, phase-frequency curves and impulse-response frequency glides, and their variation with CF.

Among linear systems sharing the same magnitude-frequency spectra, minimum-phase systems exhibit the shortest delays, which are determined by, and can be computed from, the magnitude-frequency spectra [(

Bode, 1945); pp. 204–212 of (

Papoulis, 1962);(

Goldstein et al., 1971)]. Other linear systems consist of combinations of a minimum-phase, or filter, components and an all-pass components, such as pure (frequency-independent) delays. In general, non-minimum-phase linear systems can be decomposed into minimum-phase and all-pass components [pp. 132–133 of (

Papoulis, 1977)].

Temchin et al. (2005) have shown that the near-CF group delays of putative basilar-membrane (BM) impulse responses (derived from Wiener kernels of ANF responses to noise) are well described as combinations of frequency-independent delays or latencies and (time-consuming) filters [see Fig. 11 of (

Temchin et al., 2005)]. However, it is not clear whether BM responses have the minimum-phase property (de Boer and Nuttall, 1996;

de Boer, 1997;

Recio-Spinoso et al., 2010).

Here we use minimum-phase computations not to determine whether cochlear responses have the minimum-phase property but solely to derive phase-frequency curves from magnitude-frequency curves in a systematic and consistent manner. Specifically, synthetic transfer functions (STFs) are constructed by combining filter functions, derived via minimum-phase computations from modified average ANF FTCs (

Temchin et al., 2008), and signal-front delays, specified by the latencies of BM and ANF responses to intense clicks [from Fig. 13A of (

Temchin et al., 2005)]. The STFs predict many features of phase-frequency curves of cochlear responses to tones, including their shape transitions in the regions with characteristic frequencies of 1 kHz and 3–4 kHz, and the phases and group delays (i.e., the negatives of the phase-frequency slopes) at the CF. The STFs also predict the polarities of the frequency sweeps of impulse responses and their transition at CFs around 1 kHz. Preliminary results of this research were published in an abstract (

Temchin et al., 2009).