Gender differences in voluntary cough sound spectra demonstrated by an inverse power law analysis

During a voluntary cough, sound is generated within the airways of the lung and then travels through the upper respiratory tract before exiting the body through the oral cavity. For this reason the cough sound contains important information concerning both the sound source and the structure and function of the airways. The spectrum of a cough sound pressure wave has been shown to be composed of a broadband of frequencies which result from a complex process that follows a 1/f^β power law relationship. A 1/f^β power law function is a characteristic of one over f noise. Preliminary studies indicate that there are significant differences in the exponent β of cough sound power spectra between men and women control subjects. It seems likely that dissimilarities in the organization and size of the airways between genders may account for these differences.