A novel stress monitoring method through stress-induced respiratory alterations: non-contact measurement of respiratory V(T)/T(I) alterations induced by stressful sound using a 10 GHz microwave radar

Abstract

We have developed a non-contact stress monitoring system which measures respiratory V(T)/T(I) (tidal volume/inspiration time) alterations using a 10 GHz microwave radar. The measurable distance of the system is 50 cm, which is 10 times longer than our previously developed stress monitoring system which measures heart rate variability using a 24-GHz microwave-radar. The study was conducted with eight subjects (23 ± 1years old) to evaluate the efficacy of the system. An audio stimulus at 95 dB sound pressure level was presented to the subjects following a silent period of 120 seconds. During the silent period, V(T)/T(I) averaged 826 ± 384 ml s⁻¹, while it increased significantly (p < 0.05) with an average of 1227 ± 704 ml s⁻¹ during audio stimulus low frequency component (LF)/high frequency component (HF), which reflects sympatho-vagal valance, showed a peak during audio stimuli. This paper aims to study the efficacy of the non-contact stress monitoring system for its future applications in many fields including health and safety.

Keywords::

• Non-contact
• microwave radar
• respiration
• V(T)/T(I)
• audio stimuli
• stress

Declaration of interest: Authors declare no conflict of interest.