During breath infusion practice on April 9, 2020, I experienced a soft rumbling sound. It began at the base muladhara chakra in the lower torso. It spread upwards through the trunk, into the neck and head. It was similar to soft rumbling of thunder during a rainstorm.
It moves up in waves which I could see. This was the kundalini which is usually an inner energy experience with or without visual display. This experience is part of the trunk kundalini experience which is not the sushumna nadi central spinal passage arousal but which is an arousal within the trunk of the body in various parts of it. This verifies that kundalini has a feelings aspect, a visionary aspect and a sound aspect.