ancient woodwind instrument
竽 refers to a specific ancient woodwind instrument, similar to a mouth organ or panpipe, made from bamboo.
竽 combines 竹 (bamboo) with 于, which likely contributes a phonetic element. The character represents a bamboo wind instrument.
The bamboo top 竹 hints at the material, and the lower part 于 resembles a row of pipes. Picture an ancient musician blowing into a bamboo panpipe: 竽.
For ウ, imagine the soft, breathy sound of the instrument: 'oo' as you blow into the bamboo pipes. The 'oo' sound cues ウ.
yu; free reed wind instrument used in ancient China and Nara-period Japan