sound, noise, final particle
唎 centers on vocal sound: a noise, a voice, or a spoken particle. The meanings are narrow and closely related to audible utterance.
唎 combines 口 (mouth) with 利, which likely contributes the sound. The exact historical development is uncertain, but the structure suggests a phono-semantic compound related to mouth sounds.
A mouth 口 beside the component 利, which here can be thought of as a sharp blade cutting the air to produce a clear sound. Imagine a mouth shaping a sharp, distinct noise.
For リ, picture a mouth making a ringing 'ree' sound, like a high-pitched noise: ree -> リ.