Formant analysis of breath and snore sounds

Formant frequencies of snore and breath sounds represent resonance in the upper airways; hence, they change with respect to the upper airway anatomy. Therefore, formant frequencies and their variations can be examined to distinguish between snore and breath sounds. In this paper, formant frequencies of snore and breath sounds are investigated and automatically grouped into 7 clusters based on K-Means clustering. First, formants clusters of breath and snore sounds of all subjects were investigated together and their union were calculated as the most probable ranges of the formants. The ranges for the first four formants which span the main frequency components of breath and snore sounds were found to be [20-400]Hz, [270-840]Hz, [500-1380]Hz and [910-1920]Hz. These ranges were then used as priori information to recalculate the formants of snore and breath sounds separately. Statistical t-test showed the 1^st and 3^rd formants to be the most characteristic features in distinguishing the breath and snore sounds from each other.