Christer Ahlström

Phonocardiographic Signal Processing: a Nonlinear Approach Christer Ahlström

Phonocardiography and auscultation are noninvasive,low-cost and accurate methods for assessing heartdisease. However, diagnosis by auscultation requiresgreat experience and there is considerableinter-observer variation. The primary aim of thisbook is to present objective signal processing toolsable to extract information from thephonocardiographic (PCG) signal. The PCG signal istraditionally analyzed and characterized bymorphological properties in the time domain, byspectral properties in the frequency domain or bynonstationary properties in a joint time-frequencydomain. Besides reviewing these techniques, this bookalso covers recent advancements in nonlinear PCGsignal analysis. Especially, Takens'' delay embeddingtheorem is used to reconstruct the underlyingsystem''s state space. This processing step provides ageometrical interpretation of the signal''s dynamics,whose structure can be used for both systemcharacterization and classification as well as forsignal processing tasks such as detection andprediction. In a world where modern health care isstriving for time- and cost-contained point-of-caretesting, it is now time to bring phonocardiography upto date.