Pitch is coded by different mechanisms above and below roughly 3 kHz

Evidence

Across the studies we have discussed, we see a major trend: Pitch perception seems to follow a different pattern at low frequencies versus high frequencies. It follows, then, that a different mechanism is responsible for coding pitch at high frequencies, above about 3 kHz, vs. low frequencies, below about 3 kHz. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1271