range of peaks, name of mountain
嶧 centers on a connected series of mountain peaks, a mountain range. It is also used as a proper name for a specific mountain.
嶧 combines 山 (mountain) with 睪, which likely contributes the sound and relates to the idea of a chain or series, fitting the meaning of a mountain range.
The left side 山 is a mountain, and the right side 睪 looks like a stack of peaks connected together. Picture a chain of mountains stretching across the horizon.
For エキ, imagine an echo (エキ) bouncing between the peaks of a mountain range: echo -> エキ, and the sound travels along the connected peaks.