Wonder how old those walls were. Makes one postulate that the constant bombardment of sound waves on the walls of Jericho weaken them substantially with the 7th day “shout” finishing them off.
Regardless, God can flatten any wall—and He doesn’t always reveal the details in Scripture—as, for example, exactly how He stopped the sun and moon for Joshua, or brought the shadow back ten steps for Hezekiah, or arranged the star for the magi.