talk indistinctly and falteringly
嚅 centers on speech that is unclear and hesitant: talking indistinctly, mumbling, or faltering in one's words.
嚅 combines 口 (mouth) with 需, which likely contributes the sound and may relate to softness or hesitation, fitting the idea of faltering speech. The exact historical development is uncertain.
The mouth 口 beside 需, which looks like rain 雨 over 而, suggests speech that is as soft and hesitant as a light drizzle: words that falter and are hard to catch.
For ジュ, imagine someone mumbling so indistinctly that it sounds like 'jew... jew...' — a soft, faltering sound that matches the reading ジュ.