BioSignetics Corporation
                                                                    Digital Stethoscope Company                             

Heart Energy Signature is very Different from a Standard Spectrogram

Typical clinical complaint with the spectrogram is that it can not separate S1 from the
murmur or allow to separate S2 clearly or to see A2 and P2 components clearly. Same
goes for S3 and S4 sounds. We show example spectrogram below to illustrate that.

             S1       Murmur     S2      S3          
Original recording (using third party Music Editing Software)

Spectrogram

Waveletogram (obtained using wavelet transform)

Spectrograms display frequency as vertical axis and time as horizontal and plot sound intensity in decibel in color. They utilize Short Term Window Fourier Transform (SWFT) that is a first order
method and is subject to the uncertainty principle, whereby one can not achieve simultaneous resolution in frequency and in time. Correspondingly, spectrogram image is window size
dependent. See images below (as window size increases time resolution decreases and
frequency resolution improves). 

Window size: 1024	Window Size: 2048
Window Size: 4096	Original Heart Sound Recording

Heart Energy Signature Method Spectrogram of the same heart sound recording is shown below.
It is a second order method and can simultaneously resolve both time and frequency and can
separate all key components of the heart sound as it is shown on the figures below.

                         S1           Murmur              S2(sp)         S3                                 S1       murmur                S2

                          Murmur                                                   Split S2                         S3      

Further detail shows first heart beat without S1 - murmur, S2 and S3. Note clear separation of Murmur,
A2 and P2 components. S2 and S3 are clearly visible.

Also S1 shows clear separation of mitral and tricuspid components on the Energy
Power vs. Time Plot

  S1:          (1)    (2) 

and S2 also shows clear A2 and P2 on the same plot

             A2        P2                                        S3  

All Materials and Images are subject to the Copyright.
Copyright: 2004-2008 BioSignetics Corporation
Last modified: 01/01/08