Final answer:
Lower frequencies are detected at the apex of the cochlea, while higher frequencies are detected at the base. Pitch in the inner ear is encoded using both place coding and rate coding, with place coding being predominant for very high frequencies.
Step-by-step explanation:
Lower frequencies ranging from 20 Hz to 200 Hz are detected at the apex of the cochlea. This is because these sound waves with lower frequencies travel farther along the basilar membrane before causing significant excitation of the membrane. Hair cells located at the apex are activated by these low frequencies, while high frequencies activate the hair cells at the base of the cochlea, near the round and oval windows.
The primary mechanism for encoding pitch in the inner ear is through both place coding and rate coding. Place coding is where different portions of the basilar membrane are sensitive to different frequencies, with low frequencies activating the apex and high frequencies the base. Rate coding also contributes, with the rate of action potentials enhancing pitch perception, especially for sounds up to about 4000 Hz. At much higher frequencies, place cues are mainly used for encoding.