
81-11Ventilation Measurement
An experimental setup for the measurement of respiratory input impedance is shown in Figure 81.8.
A suitable soware provides
• Generation of a pseudorandom sequence (typically obtained by summing the rst 25 harmonics
of 2 Hz with random phases) which, aer digital-to-analog conversion and proper power ampli-
cation, drives a large (20–30 cm diameter) loudspeaker
•
Acquisition of two blocks of pressure and ow samples: 2 × 4096 data are collected in a 16 s run
at a sampling rate of 256 samples/s
• Processing of data in order to obtain the desired Z
R
(f) function in the typical interval 2–48 Hz
e
bias tube allows ...