duckweed
蘋 refers to duckweed, a small floating aquatic plant.
蘋 combines the grass radical 艹 with 頻, which likely provides the sound. The character was used for duckweed, a plant floating on water.
The grass radical 艹 sits above 頻, like duckweed floating on the surface of water. Think of the plant as a frequent (頻) sight on ponds.
For ヒン, imagine a tiny duckweed plant letting out a high-pitched 'hin!' sound as it drifts on the water: hin -> ヒン.
Nanpin school of Japanese painting (Edo period)