As an adjective shriekier
is comparative of shrieky.
As a noun shrieker is
one who shrieks.
shriekier
English
Adjective
(head)
(shrieky)
shrieky
English
Adjective
(
er)
Inclined to shriek, or characterised by shrieks.
- I can't wait for the neighbours' shrieky kids to go back to school.