Speed of low-frequency sound through lungs of normal men

Abstract

vesicular lung sound through the lung has not been clearly established. In a recent study (J. Appl. Physiol.: Respirat. En-viron. Exercise Physiol. 54: 304-308, 1983), Rice measured the speed of sound through the parenchyma of excised horse lungs and found it to be 25-70 m/s (< 20 % the speed of sound in air). Filling the lung with helium or sulfur hexafluoride changed the speed of transmission by less than lo%, indicating nongas propagation. The present study was designed to measure the speed of sound through human lungs in vivo. Five healthy, nonsmoking males (aged 27-38 yr) were studied. A microphone was placed on the neck beneath the larynx and another at each of eight locations on the chest wall. Measurements were made at functional residual capacity. White noise was band-pass filtered between 125 and 500 Hz, amplified, and delivered to a loudspeaker connected to a mouthpiece. The speed of soun