Am. J. Respir. Crit. Care Med.,
Volume 162, Number 3, September 2000, 905-909
The Relationship between Normal Lung Sounds,
Age, and Gender
VOLKER
GROSS,
ANKE
DITTMAR,
THOMAS
PENZEL,
FRANK
SCHÜTTLER,
and
PETER
von WICHERT
Department of Medicine, Philipps-University, Marburg, Germany
Auscultation is one of the most important noninvasive and feasible
methods for the detection of lung diseases. Systematic changes in
breathing sounds with increasing age are of diagnostic importance. To investigate these changes, we recorded lung sounds taken from four locations in the posterior thorax of 162 subjects, together with airflow. The data were analyzed according to age, sex, and smoking habit. In order to describe the power spectrum of the lung sounds, we calculated mean and median frequency,
frequency with the highest power, and a ratio (Q) of relative
power of the two frequency bands of 330 to 600 Hz and 60 to 330 Hz. Linear regression analysis was used as a measurement of age-dependence of these variables. Significant differences in Q were
found in men versus women (p < 0.05), but not in smokers versus
nonsmokers. Within the groups, a small but significant correlation
existed between Q and age (r2
0.1, p < 0.05). For both men and
women, a slight increase of the relative power in the frequency
band of 330 to 600 Hz was recorded with increasing age. However, on the basis of large individual variations, these small
changes (
Q ~ 5%, SD(Q)
± 5%) have no clinical significance
and need not to be considered in the automatic detection of lung
diseases by analyzing lung sounds.