<div dir="ltr">Thanks Makoto, as I understand  (vaguely) these frequency ranges are to safeguard against radio frequency (RF) interferences that are high in range of Mhz to Ghz but they interfere the EEG signal at low frequency.  <div>Thanks Valia, the number is not for acoustic shielding - it is a kind of the measure of shielding  effectiveness is expressed in decibels (dB), e.g., 40dB means 99% of EM interference blocked.</div><div><div><br></div><div><br></div><div>Archana</div><div><br></div><div><div><br></div><div><br></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Oct 17, 2014 at 9:20 AM, Valia Rodriguez <span dir="ltr">&lt;<a href="mailto:valia.rodriguez@infomed.sld.cu" target="_blank">valia.rodriguez@infomed.sld.cu</a>&gt;</span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
  
    
  
  <div text="#000000" bgcolor="#FFFFFF">
    <br>
    Hi!<br>
    <br>
    I think it is strange the range of frequencies for filtering and the
    association with dB.<br>
    Could it be that the information provided by the company building
    was making reference to the acoustic isolation for the cage/room?<br>
    <br>
    As far as I know when a shielded room or cage is builded not
    especific filters for electrical frecuencies are used. What it is a
    requirement is to make a good earth and to provide some acoustic
    shielding. I think the values refer to the later.<span><font color="#888888"><br>
    <br>
    Valia</font></span><div><div><br>
    <br>
    <br>
    <br>
     <br>
    <div>On 16/10/2014 19:09, Makoto Miyakoshi
      wrote:<br>
    </div>
    <blockquote type="cite">
      <div dir="ltr">Dear Archana,
        <div><br>
        </div>
        <div>EEG signal range is 1-500Hz. Not even kiloHertz. Because of
          this, any shield room is fine (i.e. does not work anyway).</div>
        <div><br>
        </div>
        <div>The most problematic environmental artifact is 50/60Hz line
          noise. This is hard to shield because of low frequency. I
          heard that you need a type of magnetic shield instead of
          ordinary copper ones to shut it off.</div>
        <div><br>
        </div>
        <div>I&#39;ve seen labs that is not shielded. Their data tend to
          have higher 50/60Hz line noise, but we can low-pass the data
          below that. Our Mobilab does not have a shield either.</div>
        <div><br>
        </div>
        <div><span style="font-family:arial,sans-serif;font-size:13.1428575515747px">&gt;
            I would like to know what does the cutoff in Hz represent.</span><br>
        </div>
        <div><span style="font-family:arial,sans-serif;font-size:13.1428575515747px"><br>
          </span></div>
        <div><span style="font-family:arial,sans-serif;font-size:13.1428575515747px">The
            noise level is guaranteed to be attenuated to the specified
            levels.</span></div>
        <div><br>
        </div>
        <div>Makoto</div>
        <div><br>
        </div>
        <div><br>
        </div>
        <div class="gmail_extra"><br>
          <div class="gmail_quote">On Wed, Oct 15, 2014 at 10:20 PM,
            Archana Singh <span dir="ltr">&lt;<a href="mailto:sine.arc@gmail.com" target="_blank">sine.arc@gmail.com</a>&gt;</span>
            wrote:<br>
            <blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
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                      <div style="padding-bottom:20px;padding-left:8px">
                        <div style="font-family:arial,sans-serif;font-size:medium;margin-left:44px">
                          <div style="font-size:13.3333339691162px;margin-bottom:0px;margin-left:0px;padding-bottom:5px">
                            <div style="overflow:hidden">
                              <div dir="ltr">
                                <div><br>
                                </div>
                              </div>
                            </div>
                          </div>
                        </div>
                        <div style="font-family:arial,sans-serif;font-size:medium;margin-left:44px">
                          <div style="font-size:13.3333339691162px;margin-bottom:0px;margin-left:0px;padding-bottom:5px">
                            <div style="overflow:hidden">
                              <div dir="ltr">
                                <div>Dear All,</div>
                                <div><br>
                                </div>
                              </div>
                            </div>
                          </div>
                        </div>
                        <div style="margin-left:44px">
                          <div style="margin-bottom:0px;margin-left:0px;padding-bottom:5px">
                            <div style="font-family:arial,sans-serif;font-size:13.3333339691162px;overflow:hidden">I
                               hope that some of you have experience
                              with construction of electric shielding
                              room for your EEG experiments. I am
                              negotiating with shieldroom companies for
                              our new EEG lab.</div>
                            <div style="font-family:arial,sans-serif;font-size:13.3333339691162px;overflow:hidden">I
                              would like to know how to interpret the
                              shielding cutoff specifications. </div>
                            <div style="font-family:arial,sans-serif;font-size:13.3333339691162px;overflow:hidden">I
                              have received various shielding
                              specifications as follows. I know 40dB
                              would be sufficient for our purpose, but I
                              would like to know what does the cutoff in
                              Hz represent. </div>
                            <div style="font-family:arial,sans-serif;font-size:13.3333339691162px;overflow:hidden"><br>
                            </div>
                          </div>
                        </div>
                        <div style="margin-left:44px">
                          <div style="margin-bottom:0px;margin-left:0px;padding-bottom:5px">
                            <div style="font-family:arial,sans-serif;font-size:13.3333339691162px;overflow:hidden"><span>100K-30MHz
                                / 40dB</span><br>
                            </div>
                          </div>
                        </div>
                        <div style="margin-left:44px">
                          <div style="margin-bottom:0px;margin-left:0px;padding-bottom:5px">
                            <div style="overflow:hidden"><span lang="EN-US"><span lang="EN-US">10-30MHz 
                                  / 80dB</span><br>
                              </span></div>
                          </div>
                        </div>
                        <div style="font-family:arial,sans-serif;font-size:medium;margin-left:44px">
                          <div style="font-size:13.3333339691162px;margin-bottom:0px;margin-left:0px;padding-bottom:5px">
                            <div style="overflow:hidden">
                              <div dir="ltr">
                                <div><span lang="EN-US">500k-500MHz
                                    / 40dB</span><br>
                                </div>
                                <div><br>
                                </div>
                              </div>
                            </div>
                          </div>
                        </div>
                        <div style="font-family:arial,sans-serif;font-size:medium;margin-left:44px">
                          <div style="font-size:13.3333339691162px;margin-bottom:0px;margin-left:0px;padding-bottom:5px">
                            <div style="overflow:hidden">Best,</div>
                            <div style="overflow:hidden">Archana</div>
                          </div>
                        </div>
                        <div style="font-family:arial,sans-serif;font-size:medium;margin-left:44px">
                          <div style="font-size:13.3333339691162px;margin-bottom:0px;margin-left:0px;padding-bottom:5px">
                            <div style="overflow:hidden"><br>
                            </div>
                            <div style="overflow:hidden"><br>
                            </div>
                            <div style="overflow:hidden"><br>
                            </div>
                          </div>
                        </div>
                        <div style="font-family:arial,sans-serif;font-size:medium;margin-left:44px">
                          <div style="font-size:13.3333339691162px;margin-bottom:0px;margin-left:0px;padding-bottom:5px">
                            <div style="overflow:hidden">
                              <div dir="ltr">
                                <div><br>
                                </div>
                                <div>__________________________________________</div>
                                <span><font color="#888888">
                                    <div>
                                      <div style="font-size:13px">
                                        <div>Archana Singh, </div>
                                        <div>ERATO Researcher,</div>
                                        <div>Functional and Chemosensory
                                          brain imaging group</div>
                                        <div>Department of Applied
                                          Biological Chemistry</div>
                                        <div>Graduate School of
                                          Agricultural and Life Sciences</div>
                                        <div>The University of Tokyo,
                                          Tokyo 113-8657</div>
                                        <div><br>
                                        </div>
                                      </div>
                                    </div>
                                  </font></span></div>
                            </div>
                          </div>
                        </div>
                      </div>
                    </div>
                  </div>
                </div>
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                        </div>
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                        </div>
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                    </div>
                  </div>
                </div>
              </div>
              <br>
              _______________________________________________<br>
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            </blockquote>
          </div>
          <br>
          <br clear="all">
          <div><br>
          </div>
          -- <br>
          <div dir="ltr">Makoto Miyakoshi<br>
            Swartz Center for Computational Neuroscience<br>
            Institute for Neural Computation, University of California
            San Diego<br>
          </div>
        </div>
      </div>
      <br>
      <fieldset></fieldset>
      <br>
      <pre>_______________________________________________
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    </blockquote>
    <br>
  </div></div></div>

</blockquote></div><br></div></div></div></div>