Report 67407: Possible wood knocks heard near Marble mountain Sno-Park

I went on a 6 mile hike starting at the Marble Mountain Sno-Park via the worm flows route south of Mount St. Helens. At 9:30am 1/2 mile up the trail I stopped for some water and stepped over to look at the rock pit. While stepping back to the trail I heard  loud wood knocking sounds for about 10-15 seconds. I listened for a few more seconds and then got my phone out to record the knocking sounds. In my recordings you can hear one powerful knock followed by faint knocking sounds. In my longer video I believe three different knocking locations can be detected. Starting with one loud strike of a tree followed by faint knocking and then a more muffled hit followed by the same faint knocking sounds. Hoping to video anything moving around, I decided to continual my hike going up another 2.5 miles until inclement weather rolled in. I made it back to my truck at 4pm without seeing or hearing anything else. With me being the only one parked at the Sno-Park when I started my hike it's clear nobody was near me at the time of the knocking. Forest road 83 is gated for the winter with only the Sno-park open.