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<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Thanks for clarification,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:#1F497D">So, “10*log_10 (uV^2/Hz)”, is basically the log-transformed power spectral density where ‘/Hz’ means the width of frequency bin or the minimal unit frequency
being analyzed.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Now, going back to my first question, I wonder these statements are ok.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Assuming that the frequency bin size is constant within a dataset, since the power spectral density, uV^2/Hz, is another form of power measure (it is perfectly
correlated with the absolute power (uV^2)), we can represent the term “10*log_10 (uV^2/Hz)” as decibel because it measure the power with respect to the unit spectral density.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Hope I’m not too wrong about this.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Thanks.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Kay Sung<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:windowtext">>>>>>>>>>>>>>>>>>>>>><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">For your second question below, the scaling is necessary to keep the power values consistent across different frequency bin widths. If you FFT longer lengths
of data, the power in any given band is split across more frequency bins. Thus, you scale by the bin width (that’s the per Hertz in the denominator) so that you can compare power values across data sets with different length FFT windows.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Hope that helps.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><i><span style="font-size:14.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Cort Horton, PhD<o:p></o:p></span></i></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Director of Research & Development<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Qneuro Inc.
</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><a href="http://www.qneuro.com"><span style="font-size:10.0pt;color:#0563C1">www.qneuro.com</span></a></span><span style="font-size:10.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Email:
</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><a href="mailto:chorton@qneuro.com"><span style="font-size:10.0pt;color:#0563C1">chorton@qneuro.com</span></a></span><span style="font-size:10.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><img border="0" width="149" height="51" id="Picture_x0020_1" src="cid:image001.png@01D1B4F9.7F727940" alt="Qneuro"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:13.0pt;font-family:"Calibri",sans-serif;color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#00337F">Kyongje (Kay) Sung, Ph.D</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#00337F">Research Associate<br>
<b>Johns Hopkins University School of Medicine</b><br>
Cognitive Neurology & Neuropsychology – Department of Neurology</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#00337F"> </span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#00337F">1629 Thames Street, Suite 350</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#00337F">Baltimore, MD 21231<br>
P 443-287-8019 | F 410-955-0188<br>
</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><a href="mailto:ksung3@jhmi.edu"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#00337F">ksung3@jhmi.edu</span></a></span><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#00337F"><br>
</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><a href="http://web.jhu.edu/cognitiveneurology/index.html"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#00337F">web.jhu.edu/cognitiveneurology/index.html</span></a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#00337F">_______________________________________________________________________________</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
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