Head biological signal detection device and biological state estimation device

A head biological signal detection device, comprising:

• a head biological signal detection sensor that includes:
• a three-dimensional knitted fabric having a pair of ground knitted fabrics facing each other at an interval and a connecting yarn knitted between the pair of ground knitted fabrics to keep the interval between the pair of facing ground knitted fabrics;
• a housing film covering the three-dimensional knitted fabric;
• and a microphone that detects sound/vibration propagated through the three-dimensional knitted fabric, the head biological signal detection sensor being disposed with an abutting surface thereof in contact with a surface of a head, to detect a head biological signal which is sound/vibration generated by cerebral blood flow;
• and
• a sensor support member with which the head biological signal detection sensor is supported on the head in a manner that the abutting surface is in contact with the surface of the head and the connecting yarn sag to make the interval between the pair of facing ground knitted fabrics narrower than that under no load,
• wherein microvibration occurring in the three-dimensional knitted fabric or the housing film due to movement of the head while the biological signal detection device is worn works as noise to generate a stochastic resonance phenomenon between the noise and the head biological signal, and the head biological signal is detected by the microphone.