Tracheal sound spectra depend on body height.
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)
Sanchez
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Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, Canada.
Pasterkamp
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D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D055592:Biophysical Phenomena; D001703:Biophysics; D001827:Body Height / Q000502:physiology*; D002648:Child; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D008297:Male; D012123:Pulmonary Ventilation; D012016:Reference Values; D012135:Respiratory Sounds / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation; D013018:Sound Spectrography / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data; D014132:Trachea / Q000502:physiology*