非谓语动词的过去分词形式作后置定语

Holes, dips, and depressions in the ground were detected in advance of potential stumbles.

There were still a few surprises, as a squeal here and there in the dark announced, but we did learn to see with our feet -- lessons in trail Braille.

问题：

请问announced是非谓语动词的过去分词形式作后置定语，修饰squeal？

There were still a few surprises, as a squeal here and there in the dark announced...

announced在这里不是过去分词，而是过去式，为as分句的谓语动词。

as引导比较分句，意为“正如...那样”，修饰前面整个主句的内容。announced在此为比喻性使用方法，意为“表明”，如下句中的使用方法：

The sound of the door slammingannouncedhis departure.“砰”的关门声表明他离开了。

There were still a few surprises, as a squeal here and there in the dark announced...

正如黑暗中不时地传来的尖叫声表明的那样，仍然有一些意料之外的事情发生。