Non-contact measurement of propagation characteristics in human wrist using pass-through airborne ultrasound

The non-contact measurement of the propagation characteristics in the human body using pass-through airborne ultrasound has been proposed. Detection and evaluation of airborne ultrasound passed through the heel have been reported. However, estimation of the speed of sound (SOS) in the heel is difficult due to large attenuation of the pass-through ultrasound. In this paper, airborne ultrasound passed through the wrist is studied. The pass-through ultrasound can be detected by pulse compression using more than 16th-order M-sequence. Attenuation of the pass-through ultrasound or the estimated SOSs in the wrist are different by the transducer position. When the transducers are set at the center of the wrist, attenuation and the SOS are 86.2 dB and 1780 m/s, respectively.