Research of the amplitude-frequency characteristics of the human chest transfer function.

The amplitude-frequency characteristics of the human chest transfer function (AFC) were studied experimentally in 12 healthy male volunteers. Chest percussion vibrations were generated and recorded using the developed hardware and software complex. Vibrations were recorded at the place of their generation using a built into the striker-vibrator accelerometer, and in four additional regions using a receiving accelerometer: in the same intercostal space, where the percussion vibrations were generated, above and below this place, and in the adjacent intercostal spaces, above and below the vibration generation place. The obtained vibration spectra for four regions were used to find AFC in the frequency range from 10 to 1000 Hz. The general median values of the AFC for each of the four regions were obtained, normalized to the distance between the striker-vibrator and the receiving accelerometer. The shape and amplitude of the AFC in different regions did not have significant differences (the maximum difference between the general normalized median values of the AFC in different regions at the same frequency did not exceed 2.70 dB/cm in the entire frequency range). The viscoelastic properties of soft tissues, to which the receiving accelerometer is attached, affect the shape of the signal recorded by the accelerometer.