Possible vocalizations on Little Si Trail outside North Bend witnessed in King County, Washington

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I was hiking at Little Si in Washington State with a friend who was visiting from out of town. It was pouring rain so we left our phones but we went anyway and started our hike sometime in the morning. We got to an interesting little part off the trail where a little waterfall was pouring off from a cliff above, maybe like 20 feet up. We turned back after that spot and started heading back but while we were walking we heard what I first thought was an alarm, but it sounded organic. At the end of the 'alarm' was a very strange vocalization like an ape mixed with human. The alarm sound happened over 10 times and at the end of each sustained holler was the strange vocalization. After the second or third alarm sound and vocalization I started making the sounds back to whatever it was. My friend and I both listened intently trying to identify what the sound could possibly be. We ruled out human right away because whatever was making that sound had a huge lung capacity and we both im...