pan pipes, flute
簫 centers on a traditional wind instrument made of multiple pipes: pan pipes or a similar flute-like instrument.
簫 combines 竹 (bamboo) with 肅, which likely contributes the sound and possibly an idea of solemnity or order, fitting a ceremonial instrument. The exact historical development is uncertain.
Bamboo 竹 on top suggests a bamboo instrument, and the lower part 肅 looks like a row of vertical pipes. Picture a set of pan pipes made from bamboo tubes.
For ショウ, imagine a show where a musician plays the pan pipes: show -> ショウ, and the bamboo pipes produce a solemn melody.