年間 6 号発行
ISSN 印刷: 2152-5102
ISSN オンライン: 2152-5110
Indexed in
Frequency Distortions Introduced by Contact Sensors in Single and Two-Channel Sensing of Respiration Noise
要約
Aspects of designing multi-channel systems for electronic recording of respiration noise from the surface of the chest cavity are examined. The suggested mathematical model is employed for calculating the frequency curves of an output signal from single- and two-channel respiration-noise pickups. It is established that at frequencies below 500 Hz chestpiece pickups whose specific mechanical impedance exceeds the specific impedance of the chest-cavity surface (heavy chestpieces) markedly affect the vibrations of the contact spot as compared with a the pickup-free chest cavity. The interaction of contact pickups with the surface wave in two-chestpiece sensing of respiration noise is investigated. It is shown that signals from closely-spaced heavy chestpieces significantly affect one another. This distorts the frequency curve of the received signal as compared with the case of single-chestpiece sensing.