Frequency responses of the breathing sound signals

Abstract

The response of the breathing signal of an individual is different with respect to activities such as phonation and physical, and the condition of the lungs itself. This response can be gauged in terms of amplitude and frequency of the breathing signals. Compare to doing the physical activities alone, one's duration of inhalation is twenty percent lower when ones commit physical actives and talking at the same time. The purpose of this paper is to determine, from power spectral density (PSD) responses, the features, and their significance of the three types of breathing signals in terms of amplitude and frequency. PSD response of eighteen breathing signals had been investigated for the purpose. The samples were six each of normal breathing, wheeze, and crackles. The amplitude and its corresponding frequency of the PSD responses of these samples were taken from the highest first and second peak. For the frequency, two additional terms had been derived from the half-power amplitude of the PSD response. In terms of amplitude, for both the first and second peak, wheeze has manifested the highest value, while crackles breathing signals possess the lowest. On the other hand, among the three types of breathing signals, the frequencies of normal breathing are the highest both at the first and second peaks. There are no significance pairs, in terms of the amplitude and frequency at the second peak of the PSD responses. In terms of amplitude, at 5% significance level, there is one significance pair at the first peak of the PSD response, which is between wheeze and crackle breathing signals. There are two significance pairs in terms of the frequency of the PSD response, which are at fPSD1 and f(low)1. However, at 10% significance level there are three significance pairs in terms of the frequency. In conclusion, the frequency of the PSD responses has more significant features than the amplitude for the recognition of the normal breathing and the abnormal breathing signals wheeze and crackle.