I experienced this once, for about 30 minutes off and on. I was in camp alone, planning on staying up as long as I could, then hunkering down in the front seat of the suburban for the rest of the night. I was parked in our camp area with my truck facing toward the corn field maybe 75' away [east]. I kept hearing what "sounded like" someone dropping a very large (volleyball/basketball) sized rock onto HARD soil.... but it was coming from inSIDE the corn and kept moving around, never coming from the same place each time. I eventually heard rustling in the corn over to my 10 o'clock position maybe 125+ feet away and lit it up with a bright spotlight just in time to see "something" very dark lowering down from the tassle level several rows back in. (maybe 3 or 4?)
I wasn't processing it very well for some reason, then about 15 minutes later, I heard a series of 5 or 6 classic vocals moving south on the other side of the river to my back. [west] It only took a couple seconds, then the realization of the "thumps" and the tall dark object lowering itself out of view hit me. I wound up leaving the camp a short time later and spent the night somewhere else. It freaked me out.
The soil is typically sandy soil for this area, and the tassle height was on average 7 to 8' high after about 3 rows in. So, I can only surmise these deep, deep thumps were coming from one of "them", but how I don't know. I assumed hitting the chest, but I couldn't prove it if I had to.
As for the OP, I would say "Don't". If you know you have Squatch in the area, you don't NEED to call or wood knock. They're not going to fall for it. Just set up camp. Do normal and abnormal things to stimulate their curiosity. If they're curious, they'll come check you out.