Subject: Re: Infrasound and Infrapitch From: "Richard M. Warren" <rmwarren@xxxxxxxx> Date: Fri, 21 Aug 2009 15:11:45 -0500 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>--Apple-Mail-40--152117405 Content-Type: text/plain; charset=WINDOWS-1252; format=flowed; delsp=yes Content-Transfer-Encoding: quoted-printable On Aug 17, 2009, at 3:33 AM, Henrik M=F8ller wrote: > I would like to point out that Guttman and Julesz ("Lower Limits of =20= > Auditory Periodicity Analysis", Letters to the Editor, JASA, Vol. =20 > 35(4), p. 610 (1963)) used periodic signals, consisting of repeated =20= > wide-band noise with repetition periods corresponding to =20 > frequencies in the low/infrasonic region. There was no fundamental =20 > in their signal, thus no low-frequency/infrasonic exposure at all. > > I agree that repetition frequency and frequency contents can easily =20= > be mistaken. In assessments of environmental noise, it is not =20 > unusual that a signal of higher frequency repeated with an =20 > infrasonic frequency is - erroneously - attributed to infrasound. =20 > Examples are broadband ventilation noise that is amplitude modulated =20= > by a low frequency, or sources of tonal noise with close frequency =20 > that cause beating at a low frequency. However, the sensation is =20 > completely different, whether the fundamental is there or not. ~SNIP~ > Richard M. Warren skrev: >> >> >> The term infrasound can be misleading; while the frequency =20 >> threshold for hearing sinusoidal tones (at a reasonable amplitude) =20= >> is roughly 20 Hz, holistic frequency perception of complex =20 >> waveforms (e.g., iterated noise segments) continues for another =20 >> five octaves of =93infrapitch=94 below 20 Hz. Guttman and Julesz =20 >> (1963) found that a percept they called =93whooshing=94 occurred from = =20 >> roughly 0.5 to 4 Hz, =93motorboating=94 from 4 Hz to 20 Hz. A noisy =20= >> pitch is heard from 20 to 100 Hz, and a pure noiseless pitch with =20 >> interesting timbres from 100 Hz up to 16 or 20 kHz. Thus, =20 >> infrapitch and pitch form a seamless continuum of perceptual =20 >> =93iterance=94 extending for 15 octaves for stochastic waveforms, =20 >> subserved by partially overlapping neural mechanisms of periodicity =20= >> detection and place detection. >> >> Studies of infrapitch, since the pioneering study of Guttman and =20 >> Julesz, have been conducted by Irwin Pollack, Christian Kaernbach, =20= >> and myself. Infrapitch detection has also been studied in nonhuman =20= >> vertebrates. >> Infrapitch periodicity is quite different from =93broadband ventilation =20= noise that is amplitude modulated by a low frequency.=94 Acoustically, =20= a Repeated Frozen Noise segment (RFN) has a line spectrum consisting =20 of all integral multiples of the repetition frequency, each harmonic =20 having a randomly determined amplitude and phase. Only harmonics =20 within the range of roughly 20 Hz to 20 kHz can contribute to =20 audibility. However, RFNs having repetition frequencies from 0.5 Hz =20 to 20 Hz can be heard as patterns based on unresolved harmonics. For =20= example, a 2 Hz RFN has thousands of harmonics in the audible range =20 (20, 22, 24, 26, =8520,000 Hz) which cannot be resolved because of their = =20 close spacing. But they do create different periodic patterns within =20= each critical band. Each pattern has the identical repetition =20 frequency of 2 Hz (as can be heard when a 1/3-octave is swept through =20= the spectrum). RFNs above 20 Hz can be considered as stochastic =20 complex tones without the special amplitude and phase characteristics =20= of specific complex tones such as pulse trains, voices, and musical =20 instruments. For example, RFNs with a repetition period of 5 ms are =20 200 Hz complex tones having no hint of noise; each of these individual =20= RFNs has a unique exceptionally rich timbre based upon its particular =20= amplitude and phase spectrum. Jim Bashford and I have used RFNs to study pitch and infrapitch =20 perception starting in 1981 (=93Perception of acoustic iterance: Pitch =20= and Infrapitch,=94 Perception & Psychophysics, 29, 395-402). Richard M. Warren Research Professor and Distinguished Professor Emeritus Department of Psychology University of Wisconsin-Milwaukee PO Box 413 Milwaukee, WI 53201 --Apple-Mail-40--152117405 Content-Type: text/html; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable <html><body style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; = -webkit-line-break: after-white-space; "><div><div style=3D"word-wrap: = break-word; -webkit-nbsp-mode: space; -webkit-line-break: = after-white-space; "><div><div style=3D"word-wrap: break-word; = -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; = "><div><div style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; = -webkit-line-break: after-white-space; "><div = apple-content-edited=3D"true"><span class=3D"Apple-style-span" = style=3D"font-size: 12px; ">On Aug 17, 2009, at 3:33 AM, Henrik M=F8ller = wrote:</span></div><div><div style=3D"word-wrap: break-word; = -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; = "><div><div style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; = -webkit-line-break: after-white-space; "><div><font = class=3D"Apple-style-span" size=3D"3"><span class=3D"Apple-style-span" = style=3D"font-size: 12px;"><br = class=3D"Apple-interchange-newline"></span></font><blockquote = type=3D"cite"> <div bgcolor=3D"#ffffff" text=3D"#000000"><font = class=3D"Apple-style-span" size=3D"3"><span class=3D"Apple-style-span" = style=3D"font-size: 12px;"> 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 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. <font = class=3D"Apple-style-span" color=3D"#000000"><span = class=3D"Apple-style-span" style=3D"font-size: medium;"><font = class=3D"Apple-style-span" color=3D"#144FAE" size=3D"3"><span = class=3D"Apple-style-span" style=3D"font-size: = 12px;"><br></span></font></span></font></span></font></div></blockquote><f= ont class=3D"Apple-style-span" size=3D"3"><span class=3D"Apple-style-span"= style=3D"font-size: 13px;"><br></span></font></div><div><font = class=3D"Apple-style-span" size=3D"3"><span class=3D"Apple-style-span" = style=3D"font-size: 13px;">~SNIP~</span></font></div><div><font = class=3D"Apple-style-span" size=3D"3"><span class=3D"Apple-style-span" = style=3D"font-size: 13px;"><br></span></font></div></div></div><div><div = style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; = -webkit-line-break: after-white-space; "><div><blockquote = type=3D"cite"><div bgcolor=3D"#ffffff" text=3D"#000000"><font = class=3D"Apple-style-span" size=3D"3"><span class=3D"Apple-style-span" = style=3D"font-size: 12px;">Richard M. Warren skrev: </span></font> = <blockquote cite=3D"mid:20090814172353.4063567F2@xxxxxxxx" = type=3D"cite"> <div><font class=3D"Apple-style-span" size=3D"3"><span = class=3D"Apple-style-span" style=3D"font-size: 12px;"><br></span></font> = </div><font class=3D"Apple-style-span" size=3D"3"><span = class=3D"Apple-style-span" style=3D"font-size: 12px;"> The term = infrasound can be misleading; 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. Guttman and Julesz (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. A noisy pitch is heard from = 20 to 100 Hz, and a pure noiseless pitch with interesting timbres from = 100 Hz up to 16 or 20 kHz. Thus, infrapitch and pitch form a = seamless continuum of perceptual =93iterance=94 extending for 15 octaves = for stochastic waveforms, subserved by partially overlapping neural = mechanisms of periodicity detection and place = detection. </span></font><div><font = class=3D"Apple-style-span" size=3D"3"><span class=3D"Apple-style-span" = style=3D"font-size: 12px;"><br></span></font> </div> <div><font = class=3D"Apple-style-span" size=3D"3"><span class=3D"Apple-style-span" = style=3D"font-size: 12px;">Studies of infrapitch, since the pioneering = study of Guttman and Julesz, have been conducted by Irwin Pollack, = Christian Kaernbach, and myself. Infrapitch detection has = also been studied in nonhuman vertebrates.<br = class=3D"Apple-interchange-newline"></span></font> </div> <div><font = class=3D"Apple-style-span" size=3D"3"><span class=3D"Apple-style-span" = style=3D"font-size: 12px;"><br></span></font> </div> <div> <span = class=3D"Apple-style-span" style=3D"border-collapse: separate; color: = rgb(0, 0, 0); font-family: Helvetica; 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; word-spacing: 0px; "><span class=3D"Apple-style-span" = style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: = Helvetica; 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; = word-spacing: 0px; "><font class=3D"Apple-style-span" size=3D"3"><span = class=3D"Apple-style-span" style=3D"font-size: 12px;"> = </span></font></span></span></div></blockquote></div></blockquote></div></= div><br><br></div><div><!--StartFragment--> <div = class=3D"MsoNormal">Infrapitch periodicity is quite different from = =93broadband ventilation noise that is amplitude modulated by a low = frequency.=94<span style=3D"mso-spacerun: yes"> = </span>Acoustically, a Repeated Frozen Noise segment (RFN) has a line = spectrum consisting of all integral multiples of the repetition = frequency, each harmonic having a randomly determined amplitude and = phase.<span style=3D"mso-spacerun: yes"> </span>Only harmonics = within the range of roughly 20 Hz to 20 kHz can contribute to = audibility.<span style=3D"mso-spacerun: yes"> </span>However, RFNs = having repetition frequencies from 0.5 Hz to 20 Hz can be heard as = patterns based on unresolved harmonics.<span style=3D"mso-spacerun: = yes"> </span>For example, a 2 Hz RFN has thousands of harmonics in = the audible range (20, 22, 24, 26, =8520,000 Hz) which cannot be = resolved because of their close spacing. But they do create = different periodic patterns within each critical band. Each = pattern has the identical repetition frequency of 2 Hz (as can be heard = when a 1/3-octave is swept through the spectrum).<span = style=3D"mso-spacerun: yes"> </span>RFNs above 20 Hz can be = considered as stochastic complex tones without the special amplitude and = phase characteristics of specific complex tones such as pulse trains, = voices, and musical instruments.<span style=3D"mso-spacerun: yes"> = </span>For example, RFNs with a repetition period of 5 ms are 200 Hz = complex tones having no hint of noise; each of these individual RFNs has = a unique exceptionally rich timbre based upon its particular amplitude = and phase spectrum.<span style=3D"mso-spacerun: = yes"> </span></div><div class=3D"MsoNormal"><o:p></o:p></div> <div = class=3D"MsoNormal"> <o:p></o:p></div> <font = class=3D"Apple-style-span" size=3D"4"><span class=3D"Apple-style-span" = style=3D"font-size: 14px;">Jim Bashford and I have used RFNs to study = pitch and infrapitch perception starting in 1981 (=93Perception of = acoustic iterance: Pitch and Infrapitch,=94 </span></font><font = class=3D"Apple-style-span" size=3D"4"><span class=3D"Apple-style-span" = style=3D"font-size: 14px;"><i>Perception & = Psychophysics</i></span></font><font class=3D"Apple-style-span" = size=3D"4"><span class=3D"Apple-style-span" style=3D"font-size: 14px;">, = 29, 395-402).</span></font><!--EndFragment--> </div><div><font = class=3D"Apple-style-span" face=3D"Times" size=3D"4"><span = class=3D"Apple-style-span" style=3D"font-size: = 16px;"><br></span></font></div><div><span class=3D"Apple-style-span" = style=3D"font-size: 13px; "><font class=3D"Apple-style-span" = size=3D"4"><span class=3D"Apple-style-span" style=3D"font-size: 14px; = "><b>Richard M. Warren</b></span></font> </span></div><div><font = class=3D"Apple-style-span" face=3D"Times" size=3D"4"><span = class=3D"Apple-style-span" style=3D"font-size: 16px;"><span = class=3D"Apple-style-span" style=3D"font-family: Helvetica; font-size: = medium; "><div><span class=3D"Apple-style-span" style=3D"border-collapse: = separate; color: rgb(0, 0, 0); font-family: Helvetica; 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; word-spacing: = 0px; -webkit-border-horizontal-spacing: 0px; = -webkit-border-vertical-spacing: 0px; = -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: = auto; -webkit-text-stroke-width: 0px; "><span class=3D"Apple-style-span" = style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: = Helvetica; 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; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; = -webkit-border-vertical-spacing: 0px; = -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: = auto; -webkit-text-stroke-width: 0px; "><div style=3D"word-wrap: = break-word; -webkit-nbsp-mode: space; -webkit-line-break: = after-white-space; "><div><div>Research = Professor </div><div> and Distinguished Professor = Emeritus</div><div>Department of Psychology</div><div>University of = Wisconsin-Milwaukee</div><div>PO Box 413</div><div>Milwaukee, WI = 53201</div></div><div><br = class=3D"webkit-block-placeholder"></div></div></span></span></div></span>= </span></font></div></div></div><br></div></div><br></div></div><br></div>= </div><br></body></html>= --Apple-Mail-40--152117405--