She means the lute that is heard by those about to die.

Queen:

I have heard Gog-Owza, the lutanist, playing his lute. And I shall die,
O I shall die.

King Karnos:

No. No. No. You have not heard Gog-Owza. Send for her maidens, send for
the Queen's maidens.

Queen:

I have heard Gog-Owza playing, and I shall die.

King Karnos:

Hark. Why, I hear it too. That is not Gog-Owza, it is only a man with a
lute; I hear it too.

Queen:

O the King hears it too. The King will die. The great King will die. My
child will be desolate for the King will die. Mourn, people of the
jungle. Mourn, citizens of Thek. And thou, O Barbul-el-Sharnak, O
metropolitan city, mourn thou in the midst of the nations, for the
great King will die.

King Karnos: