a sucking sound like the one produced when you are walking on soft, wet ground

中文解释

（如走在湿软土地上似的）发吧唧声，发扑哧声 As the hikers walked down the path by the house, she could hear the squelch of their boots in the mud. 徒步旅行者们从房子旁的小径走过时，她能听见他们的靴子吧唧吧唧踩在泥里的声音。