Pure-tone temporal coding is low-frequency only, but complex tones use both fiber types.

Evidence

For pure tones, then, the temporal code is a low-frequency phenomenon. For complex tones, however, the temporal code is present in both highand low-frequency fibers. … Given that fundamental frequency is represented as individual harmonics but also in the repetition rate, both highand low-frequency auditory nerve fibers can code for the fundamental frequency. Low-frequency fibers will phase lock to individual harmonic components, whereas high-frequency fibers will phase lock to the fluctuation rate of the envelope. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1221