This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
嗘 is a rare character composed of 口 (mouth) and 奚 (a phonetic component). Its exact historical development is uncertain.
With 口 (mouth) on the left and 奚 on the right, 嗘 might relate to a sound or voice, but its meaning is unclear.
For ケイ, imagine a mouth (口) making a sharp 'kay' sound: kay -> ケイ, though the kanji's meaning is uncertain.