Description  Claims  Drawing  Cited references 

US8424527B   [0016] 
US20130046181A   [0016] 
US2006037615A1   [0017] 
US2013289401A1   [0017] 
US6440083B1   [0017] 
US6142952A   [0017] 

Airway area by acoustic reflection: the two-microphone method   [0017] 
A bioacoustics method for timing of the different phases of the breathing cycle and monitoring of breathing frequency   [0084] 
Lung Capacity Estimation Through Acoustic Signal of Breath   [0085]