Wail

I have within me a trapped wail.

Wail
verb intransitive
to express sorrow with a prolonged cry {yuppers, that's what is trapped}
to make mournful sounds, as in the wail of the wind

noun
a wailing cry or any similar sound.

wail is also an onomotopoetic homonym.

whatever wail is
my wail is trapped. when it releases ....... ?
the world ends not with a bang
but with a wail.
and the whales wailed.
whatever