It's as if air bubbles are repeatedly rising from underwater, reaching the surface, and disappearing, and a balloon-like aura is intensifying in my head, pushing upwards and releasing towards the top. This repeats many times.

The tension from the center of my head to the lower half, including my throat and body, has eased considerably, but there are still stiff areas from the center of my head to the top, and I am continuing meditation while releasing them with a "creak," "crack," or "pop" sound. In addition to that "crack" feeling, there are also simply sensations of being pushed and then returning, and this repeats.

It's as if a balloon is inflating in the center of my head, and when the air pressure is slightly released, the balloon returns to its original shape, but when air is added again, it inflates slightly, and this repeats. This inflation and release cycle occurs approximately every 5 to 10 seconds. Each time, in addition to the sensation of inflation, there are sometimes "creak," "crack," or "pop" sounds, and I feel like I am gradually releasing it little by little.

It could be said that this is simply movement, but it is likely that the aura is being released upwards. I also feel that the aura is becoming difficult to pass through in the center of my head, and that the aura is spreading from the center and then being released upwards. I also feel that it is likely a combination of both physical and aura aspects.

In terms of the physical body, there is a rhythm of inflation and deflation, but in terms of the aura, there is not much change, and it is basically flowing to some extent, and I feel that as I continue meditating, the flow gradually improves.

The sensation of "air bubbles rising" is a combination of the physical and aura sensations, and it is a metaphor for that feeling, but in reality, they are probably separate. The physical body is repeatedly inflating and deflating, while the aura is relatively constant and flowing, and the combination of these creates the sensation of air bubbles rising from underwater.

This is based on sensory speculation, so it may be slightly different in reality, but I will note it for now.