Tracheal sound spectra depend on body height

Am Rev Respir Dis. 1993 Oct;148(4 Pt 1):1083-7. doi: 10.1164/ajrccm/148.4_Pt_1.1083.


Tracheal sounds originate from turbulent flow in upper and central airways. Turbulent flow characteristics are influenced by conduit dimensions. Because tracheal dimensions are a function of body height, we hypothesized that there should be a correlation between sound spectra and body length. We recorded tracheal sounds at standardized airflows in 21 healthy children 9.1 +/- 0.6 yr of age (mean +/- SE) and in 24 healthy adults 30.2 +/- 0.8 yr of age. A contact sensor was attached at the suprasternal notch of the sitting subject, and airflow was measured at the mouth with a calibrated pneumotachograph. Tracheal sounds were low-pass-filtered at 2.4 kHz and digitized at 10 kHz. A 2048 point FFT was applied at a successive 100-ms intervals, using a Hanning data window. Resulting spectra were normalized to a reference power of 0.1 (mV)2/5 Hz. We applied a gating algorithm to extract sounds at inspiratory flows of 1 L/s (+/- 10% tolerance), and we computed average power spectra from the collected samples. We calculated the average spectral power (Pavg), the quartile frequencies below which 25% (Q1), 50% (Q2), and 75% (Q3) of the power in the range of 50 to 2,000 Hz was contained, the spectral edge frequency (SE95) below which 95% of the power was found, and the frequency where spectral power rolled off sharply (Fcut).(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Analysis of Variance
  • Biophysical Phenomena
  • Biophysics
  • Body Height / physiology*
  • Child
  • Female
  • Fourier Analysis
  • Humans
  • Male
  • Pulmonary Ventilation
  • Reference Values
  • Respiratory Sounds / physiology*
  • Signal Processing, Computer-Assisted / instrumentation
  • Sound Spectrography / instrumentation
  • Sound Spectrography / methods
  • Sound Spectrography / statistics & numerical data
  • Trachea / physiology*