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J.J, Ward, MEd, RRT in Respiratory Care



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Technical details

  • Sound at the chest surface or at the neck was recorded with contact accelerometers (EMT25C, Siemens).  Recordings at the mouth were made with an electret microphone (ECM140, Sony).
  • Air flow was registered with a screen pneumotachograph (model 3350, Spirometrics). Inductance plethysmography (Respitrace) was used in young children to provide information about the respiratory pattern.
  • The sound signal was high-pass filtered at 7.5 Hz to remove DC offset (1st order Butterworth filter) and low-pass filtered at 2.5 kHz to avoid aliasing (8th order Butterworth filter). The original sampling rate was 10 kHz (some files were upsampled from 5 kHz).
  • Analog-to-digital conversion was performed with 16-bit quantization (AT-MIO-16x, National Instruments), using a notebook PC and R.A.L.E.® software.  Some files were originally acquired with 12-bit quantization (model 2801, DataTranslation) and have been adjusted for 16-bit presentation.
  • Signal processing involved fast Fourier transformation analysis (Hanning data window, 1024 data points, 75% overlap).

HeSCA logo

In recognition of excellence in health sciences media production, the Health Sciences Communications Association has given an Award of Merit, Computer-Based Materials, for the production of R.A.L.E.® (Respiration Acoustics Laboratory Environment).