flute-like musical instrument
嗩 refers to a flute-like musical instrument, specifically a type of ancient Chinese flute or pipe.
嗩 combines 口 (mouth) with a phonetic component that likely contributed the sound サ and relates to a flute-like instrument. The exact historical development of the right-side component is uncertain.
The mouth radical 口 on the left suggests a wind instrument. Picture a mouth blowing into a complex flute with many holes and parts, represented by the busy right side.
For サ, imagine a saxophone, a flute-like instrument, playing a smooth 'sa' note: sax -> サ, and the mouth blows into the 嗩.
—