Subject: Re: [AUDITORY] Ear Probe Mics and detecting the heartbea t? From: Zlatan Ribic <zlatan@xxxxxxxx> Date: Mon, 1 Jul 2013 09:17:43 +0200 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>This is a multi-part message in MIME format. ------=_NextPart_000_001C_01CE763B.D7A97C80 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable You are wrong. Pressure microphones have so called barometric hole (on = diaphragm or housing), limiting lowest frequency. ----- Original Message -----=20 From: alex kalinin=20 To: AUDITORY@xxxxxxxx=20 Sent: Sunday, June 30, 2013 12:54 PM Subject: Re: Ear Probe Mics and detecting the heartbea t? May be the limiting factor is your amplifier response at low = frequencies, but not the mic. Conventional one port small inner volume = condenser microphone works quite well starting from about 0 Hz. =D0=9F=D1=8F=D1=82=D0=BD=D0=B8=D1=86=D0=B0, 28 = =D0=B8=D1=8E=D0=BD=D1=8F 2013, 10:36 UTC =D0=BE=D1=82 "Jelfs, Sam" = <sam.jelfs@xxxxxxxx>: Dear List, Just a question for those of you with experience using ear probe = microphones, do you ever hear the heartbeat? I=E2=80=99ve built a couple = of in-ear microphones, and can hear my own heartbeat, but the quality is = relatively poor, and only works in very low-noise conditions. I was = looking in to using dedicated probe mics, such as Etymotic ER-7C = (http://www.etymotic.com/pro/er7c-ts.aspx) and whether that might give = me a better signal-to-noise ratio, but just wondered if anyone has any = experience of this before I buy some. Thanks Sam Jelfs -------------------------------------------------- Sam Jelfs Research Scientist Philips Research Laboratories, Eindhoven Smart Sensing & Analysis Address : High Tech Campus 36 5656 AE Eindhoven The Netherlands Tel: +31 (0)40 27 42402 e-Mail: sam.jelfs@xxxxxxxx -------------------------------------------------------------------------= --- The information contained in this message may be confidential and = legally protected under applicable law. The message is intended solely = for the addressee(s). If you are not the intended recipient, you are = hereby notified that any use, forwarding, dissemination, or reproduction = of this message is strictly prohibited and may be unlawful. If you are = not the intended recipient, please contact the sender by return e-mail = and destroy all copies of the original message. --=20 alex kalinin ------=_NextPart_000_001C_01CE763B.D7A97C80 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable =EF=BB=BF<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=3DContent-Type content=3D"text/html; charset=3Dutf-8"> <META content=3D"MSHTML 6.00.6000.17037" name=3DGENERATOR></HEAD> <BODY bgColor=3D#ffffff> <DIV><FONT face=3DArial size=3D2>You are wrong. Pressure microphones = have so called=20 barometric hole (on diaphragm or housing), limiting lowest=20 frequency.</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <BLOCKQUOTE=20 style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; = BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV> <DIV=20 style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: = black"><B>From:</B>=20 <A title=3Dav_kalinin@xxxxxxxx href=3D"mailto:av_kalinin@xxxxxxxx">alex = kalinin</A>=20 </DIV> <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A = title=3DAUDITORY@xxxxxxxx=20 href=3D"mailto:AUDITORY@xxxxxxxx">AUDITORY@xxxxxxxx</A> = </DIV> <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Sunday, June 30, 2013 = 12:54=20 PM</DIV> <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> Re: Ear Probe Mics and = detecting=20 the heartbea t?</DIV> <DIV><BR></DIV>May be the limiting factor is your amplifier response = at low=20 frequencies, but not the mic. Conventional one port small inner = volume=20 condenser microphone works quite well starting from about 0=20 Hz.<BR><BR><BR>=D0=9F=D1=8F=D1=82=D0=BD=D0=B8=D1=86=D0=B0, 28 = =D0=B8=D1=8E=D0=BD=D1=8F 2013, 10:36 UTC =D0=BE=D1=82 "Jelfs, Sam" = <<A=20 = href=3D"mailto:sam.jelfs@xxxxxxxx">sam.jelfs@xxxxxxxx</A>>:<BR> <BLOCKQUOTE class=3Dmailru-blockquote=20 style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 10px; PADDING-BOTTOM: 0px; = MARGIN: 10px; BORDER-LEFT: #0857a6 1px solid; PADDING-TOP: 0px"> <DIV> <DIV class=3D"js-helper js-readmsg-msg"> <STYLE type=3Dtext/css></STYLE> <DIV class=3Dmr_read__body id=3Dstyle_13724799280000000590><BASE=20 href=3Dhttps://e.mail.ru/ target=3D_self> <DIV id=3Dstyle_13724799280000000590_BODY> <DIV> <P><SPAN lang=3DEN-GB>Dear List,</SPAN></P> <P><SPAN lang=3DEN-GB></SPAN> </P> <P><SPAN lang=3DEN-GB>Just a question for those of you with = experience using=20 ear probe microphones, do you ever hear the heartbeat? I=E2=80=99ve = built a couple=20 of in-ear microphones, and can hear my own heartbeat, but the = quality is=20 relatively poor, and only works in very low-noise conditions. I was = looking=20 in to using dedicated probe mics, such as Etymotic ER-7C (<A=20 href=3D"http://www.etymotic.com/pro/er7c-ts.aspx"=20 target=3D_blank>http://www.etymotic.com/pro/er7c-ts.aspx</A>) and = whether that=20 might give me a better signal-to-noise ratio, but just wondered if = anyone=20 has any experience of this before I buy some.</SPAN></P> <P><SPAN lang=3DEN-GB></SPAN> </P> <P><SPAN lang=3DEN-GB>Thanks</SPAN></P> <P><SPAN lang=3DEN-GB></SPAN> </P> <P><SPAN lang=3DEN-GB>Sam Jelfs</SPAN></P> <P><SPAN lang=3DEN-GB></SPAN> </P> <P>--------------------------------------------------</P> <P> </P> <P>Sam Jelfs</P> <P>Research Scientist</P> <P><SPAN style=3D"COLOR: black">Philips Research Laboratories,=20 Eindhoven</SPAN></P> <P>Smart Sensing & Analysis</P> <P style=3D"LINE-HEIGHT: 12pt"><SPAN style=3D"COLOR: = black"></SPAN> </P> <P style=3D"LINE-HEIGHT: 12pt"><SPAN style=3D"COLOR: black">Address = : High Tech=20 Campus 36</SPAN></P> <P style=3D"LINE-HEIGHT: 12pt"><SPAN style=3D"COLOR: black">5656 = AE =20 Eindhoven</SPAN></P> <P style=3D"LINE-HEIGHT: 12pt"><SPAN style=3D"COLOR: black">The=20 Netherlands</SPAN></P> <P style=3D"LINE-HEIGHT: 12pt"><SPAN style=3D"COLOR: black">Tel: +31 = (0)40 27=20 42402</SPAN></P> <P style=3D"LINE-HEIGHT: 12pt"><SPAN style=3D"COLOR: black">e-Mail:=20 sam.jelfs@xxxxxxxx</SPAN></P> <P><SPAN lang=3DEN-GB></SPAN> </P></DIV><BR> <HR> <FONT face=3DArial color=3Dgray size=3D1>The information contained = in this message=20 may be confidential and legally protected under applicable law. The = message=20 is intended solely for the addressee(s). If you are not the intended = recipient, you are hereby notified that any use, forwarding, = dissemination,=20 or reproduction of this message is strictly prohibited and may be = unlawful.=20 If you are not the intended recipient, please contact the sender by = return=20 e-mail and destroy all copies of the original = message.<BR></FONT></DIV><BASE=20 href=3Dhttps://e.mail.ru/ = target=3D_self></DIV></DIV></DIV></BLOCKQUOTE><BR><BR>--=20 <BR>alex kalinin<BR></BLOCKQUOTE></BODY></HTML> ------=_NextPart_000_001C_01CE763B.D7A97C80--