Keening

The keening whistle of the tea kettle signaled that the water had boiled.

The keening whistle of the teapot signaled that the water was boiling.

As the fog rolled in, a keening foghorn warned ships of the treacherous rocks ahead.

The old haunted house echoed with the keening cries of unseen spirits.

The injured bird emitted a keening cry, signaling its distress.