ASMR

A few possible reasons why ASMR might be soothing: 1) whispering often only happens in close proximity, so it gives a (if not false) sense of intimacy 2) similar/related to No. 1, whispering often usually only happens one on one, so it gives an aura of focused attention and care 3) whispering might be similar, and thus reminds one, of the sounds in the womb 4) similar to a typical hushed voice used in lullabies.