Autonomous Sensory Meridian Response according to Wikipedia “is an experience characterized by a static-like or tingling sensation on the skin that typically begins on the scalp and moves down the back of the neck and upper spine. It has been compared with auditory-tactile synesthesia and may overlap with frisson. ASMR signifies the subjective experience of “low-grade euphoria” characterized by “a combination of positive feelings and a distinct static-like tingling sensation on the skin”. It is most commonly triggered by specific auditory or visual stimuli, and less commonly by intentional attention control.”
Because of the possibility of auditory stimulation, some people believe that the A of ASMR stands for Audio or Auditory.
At first I noticed this state when listening to certain music, later by accident whilst scratching the skin with a prickly fruit such as rambutan and lastly during meditation when concentrating on moving energy in the physical body or practising Kundalini Yoga. Breathing exercises during Tantric practices can also achieve this state.
There are also several audio recordings on YouTube specifically designed to trigger ASMR but I haven’t tried them yet.
Here is the Wikipedia article.
I would be interested in reading your comments if you have experienced this phenomenon.