Subject: Re: Infrasound and Infrapitch From: =?windows-1252?Q?Henrik_M=F8ller?= <hm@xxxxxxxx> Date: Mon, 17 Aug 2009 10:33:43 +0200 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>This is a multi-part message in MIME format. --------------040002080008030200040203 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by torrent.cc.mcgill.ca id n7H8XkEu021530 I would like to point out that Guttman and Julesz ("Lower Limits of=20 Auditory Periodicity Analysis", Letters to the Editor, JASA, Vol. 35(4),=20 p. 610 (1963)) used periodic signals, consisting of repeated wide-band=20 noise with repetition periods corresponding to frequencies in the=20 low/infrasonic region. There was no fundamental in their signal, thus no=20 low-frequency/infrasonic exposure at all. I agree that repetition frequency and frequency contents can easily be=20 mistaken. In assessments of environmental noise, it is not unusual that=20 a signal of higher frequency repeated with an infrasonic frequency is -=20 erroneously - attributed to infrasound. Examples are broadband=20 ventilation noise that is amplitude modulated by a low frequency, or=20 sources of tonal noise with close frequency that cause beating at a low=20 frequency. However, the sensation is completely different, whether the=20 fundamental is there or not. Best regards, Henrik Henrik M=F8ller Professor Section of Acoustics, Department of Electronic Systems Aalborg University Fredrik Bajers Vej 7 B5 DK-9220 Aalborg =D8, Denmark Phone: +45 9940 8711 (direct) Phone: +45 9940 8710 (section office) Phone: +45 9940 9940 (switchboard) Fax: +45 9815 2144 (section office) mailto:hm@xxxxxxxx (personal) mailto:acoustics@xxxxxxxx (section office) http://acoustics.aau.dk Richard M. Warren skrev: > > The term infrasound can be misleading; while the frequency threshold=20 > for hearing sinusoidal tones (at a reasonable amplitude) is roughly 20=20 > Hz, holistic frequency perception of complex waveforms (e.g., iterated=20 > noise segments) continues for another five octaves of =93infrapitch=94=20 > below 20 Hz. Guttman and Julesz (1963) found that a percept they=20 > called =93whooshing=94 occurred from roughly 0.5 to 4 Hz, =93motorboati= ng=94=20 > from 4 Hz to 20 Hz. A noisy pitch is heard from 20 to 100 Hz, and a=20 > pure noiseless pitch with interesting timbres from 100 Hz up to 16 or=20 > 20 kHz. Thus, infrapitch and pitch form a seamless continuum of=20 > perceptual =93iterance=94 extending for 15 octaves for stochastic=20 > waveforms, subserved by partially overlapping neural mechanisms of=20 > periodicity detection and place detection. =20 > > Studies of infrapitch, since the pioneering study of Guttman and=20 > Julesz, have been conducted by Irwin Pollack, Christian Kaernbach, and=20 > myself. Infrapitch detection has also been studied in nonhuman=20 > vertebrates. > > * > Richard M. Warren*=20 > Research Professor=20 > and Distinguished Professor Emeritus > Department of Psychology > University of Wisconsin-Milwaukee > PO Box 413 > Milwaukee, WI 53201 > > > > --------------040002080008030200040203 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by torrent.cc.mcgill.ca id n7H8XkEu021530 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content=3D"text/html;charset=3Dwindows-1252" http-equiv=3D"Content-Type"> </head> <body bgcolor=3D"#ffffff" text=3D"#000000"> I would like to point out that Guttman and Julesz ("Lower Limits of Auditory Periodicity Analysis", Letters to the Editor, JASA, Vol. 35(4), p. 610 (1963)) used periodic signals, consisting of repeated wide-band noise with=A0 repetition periods corresponding to frequencies in the low/infrasonic region. There was no fundamental in their signal, thus no low-frequency/infrasonic exposure at all. <br> <br> I agree that repetition frequency and frequency contents can easily be mistaken. In assessments of environmental noise, it is not unusual that a signal of higher frequency repeated with an infrasonic frequency is - erroneously - attributed to infrasound. Examples are broadband ventilation noise that is amplitude modulated by a low frequency, or sources of tonal noise with close frequency that cause beating at a low frequency. However, the sensation is completely different, whether the fundamental is there or not. <br> <br> Best regards, <br> <br> Henrik <pre class=3D"moz-signature" cols=3D"72">Henrik M=F8ller Professor Section of Acoustics, Department of Electronic Systems Aalborg University Fredrik Bajers Vej 7 B5 DK-9220 Aalborg =D8, Denmark Phone: +45 9940 8711 (direct) Phone: +45 9940 8710 (section office) Phone: +45 9940 9940 (switchboard) Fax: +45 9815 2144 (section office) <a class=3D"moz-txt-link-freetext" href=3D"mailto:hm@xxxxxxxx">ma= ilto:hm@xxxxxxxx</a> (personal) <a class=3D"moz-txt-link-freetext" href=3D"mailto:acoustics@xxxxxxxx= .dk">mailto:acoustics@xxxxxxxx</a> (section office) <a class=3D"moz-txt-link-freetext" href=3D"http://acoustics.aau.dk">http:= //acoustics.aau.dk</a></pre> <br> <br> Richard M. Warren skrev: <blockquote cite=3D"mid:20090814172353.4063567F2@xxxxxxxx" type=3D"cite"> <div><br> </div> The term infrasound can be misleading;<span>=A0=A0</span>while the frequency threshold for hearing sinusoidal tones (at a reasonable amplitude) is roughly 20 Hz, holistic frequency perception of complex waveforms (e.g., iterated noise segments) continues for another five octaves of =93infrapitch=94 below 20 Hz.<span>=A0=A0</span>Guttman and Ju= lesz (1963) found that a percept they called =93whooshing=94 occurred from roughly 0.5 to 4 Hz, =93motorboating=94 from 4 Hz to 20 Hz. =A0A noisy pi= tch is heard from 20 to 100 Hz, and a pure noiseless pitch with interesting timbres from 100 Hz up to 16 or 20 kHz.<span>=A0=A0</span>Thus, infrapitc= h and pitch form a seamless continuum of perceptual =93iterance=94 extendin= g for 15 octaves for stochastic waveforms, subserved by partially overlapping neural mechanisms of periodicity detection and place detection.<span>=A0=A0=A0</span> <div><br> </div> <div><span></span>Studies of infrapitch, since the pioneering study of Guttman and Julesz, have been conducted by Irwin Pollack, Christian Kaernbach, and myself.<span>=A0=A0</span>Infrapitch detection has also be= en studied in nonhuman vertebrates.<br class=3D"Apple-interchange-newline"> </div> <div><br> </div> <div> <span class=3D"Apple-style-span" style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: He= lvetica; font-size: 16px; font-style: normal; font-variant: normal; font-= weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; = text-indent: 0px; text-transform: none; white-space: normal; widows: 2; w= ord-spacing: 0px;"><span class=3D"Apple-style-span" style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: He= lvetica; font-size: 13px; font-style: normal; font-variant: normal; font-= weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; = text-indent: 0px; text-transform: none; white-space: normal; widows: 2; w= ord-spacing: 0px;"> <div style=3D""> <div> <div><font class=3D"Apple-style-span" size=3D"4"><span class=3D"Apple-style-span" style=3D"font-size: 14px;"><b><br class=3D"Apple-interchange-newline"> Richard M. Warren</b></span></font>=A0</div> <div>Research Professor=A0</div> <div>=A0=A0and Distinguished Professor Emeritus</div> <div>Department of Psychology</div> <div>University of Wisconsin-Milwaukee</div> <div>PO Box 413</div> <div>Milwaukee, WI =A053201</div> </div> <div><br class=3D"webkit-block-placeholder"> </div> </div> </span><br class=3D"Apple-interchange-newline"> </span><br class=3D"Apple-interchange-newline"> </div> <div><br> </div> </blockquote> </body> </html> --------------040002080008030200040203--