Subject: Re: Lateral Inversion in Spatial Hearing From: Heinrich Zimmermann <hzimmer(at)IAM.UNIBE.CH> Date: Sat, 25 Sep 1999 11:39:23 +0200This is a multi-part message in MIME format. ------=_NextPart_000_00A2_01BF074A.9D685CE0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable First Summary: Lateral Inversion in Spatial Hearing =20 On September, 2nd, I have put the following query on this list: =20 > I wonder if anybody on the Auditory List knows something about a = lateral > inversion phenomenon I discovered when preparing sounds for a series = of > experiments on spatial hearing: certain binaural recordings of > bandpass-filtered clicks with interaural time differences but without > interaural intensity differences seem to be lateralized as predicted = by > cross-correlation models in a frequency range below 2 Kilohertz but on = the > opposite side than predicted by these models in a frequency range = above > 8 Kilohertz. In response to some of your questions I have put an example sound file = for the lateral inversion phenomenon on http://Heinrich.Zimmermann.com. Thanks for the following postings: =20 Joachim Neubaum: > In dem Buch > * J. Blauert > * R=E4umliches H=F6ren > * Monographien der Nachrichtentechnik, 1964 =20 > steht was =FCber Lokalisation verschiedener Frequenzb=E4nder. > Das k=F6nnte helfen, das von Ihnen beobachtete Ph=E4nomen zu = verstehen. Harry Erwin: > I have a bat model that uses IIDs to estimate azimuth. I did this=20 > because there's a tradeoff between timing and intensity (1 dB=20 > corresponding to 47 microseconds of advance or delay in the Mexican=20 > free-tailed bat, Pollak 1988), and the bat head is too small for ITDs=20 > to work well at high frequencies (no more than 40-50 microseconds in=20 > E fuscus) while IIDs of 20-30 dB are seen due to head shadowing (see=20 > Moss and Schnitzler in Popper and Fay, ed., 1995, Hearing by Bats,=20 > Springer). At low frequencies (less than about 3 kHz), the signal in=20 > auditory nerve does track the variation, of course, and you can=20 > do cross-correlation. My model works beautifully for a single target. > You may have seeing some sort of phenomenon having to do with the=20 > time/intensity tradeoff. Assuming a head diameter of 15 cm, you're=20 > getting a ITD of about 750 microseconds at most. =20 Richard R Fabbri: > What does the time domain waveform (the "click") exiting the > bandpass look like ? > Could you send a 'scope trace ? Daniel J. Tollin: > Don't know if it is relevant to your work or not, but you might check = out > the following paper: > Tollin and Henning (1999). Some aspects of the lateralization of = echoed > sound in man. II. The role of the stimulus spectrum, J. Acoust. Soc. = AM. > 105, 838-849. > In that paper I describe a lateralization illusion in which observers > lateralize a signal opposite that expected based on the ITD in the = signal. > I also give reasons for the anomalous lateralization. S. L. J. D. E. van de Par > It is not entirely clear to me what exactly you observed, > but I assume that the clicks were lateralized to one > side below 2 kHz and to the other side above 8 kHz=20 > (or was it the case that they were lateralized to=20 > the same side but that the models predicted otherwise?). > One thing came to mind which may be important. > When binaural stimuli are presented through headphones > there may likely exist IIDs which vary as a function > of frequency due to differences in acoustic coupling of > the left and right earphones. These IIDs of course may > influence the perceived laterality. But I assume that you > have checked for that. =20 Ward Drennan > I'd be suprised anything was lateralized without ILDs at 8KHz. > Timing info is lost. > An onset asynchrony might give you a little cue, but I'd think in the > direction would be towards the leading filtered click. I don't know = the > bandwidths, the onset characteristics, the > delay times or the precise levels--- a 1 dB difference in level = between the > left and right ears could give you a lateralization at 8 KHz-- = expecially if > there were no onset asynchronies. ------=_NextPart_000_00A2_01BF074A.9D685CE0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META content=3D"text/html; charset=3Diso-8859-1" = http-equiv=3DContent-Type> <META content=3D"MSHTML 5.00.2614.3500" name=3DGENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=3D#ffffff> <DIV><FONT face=3DArial size=3D2> <DIV><FONT face=3DArial size=3D2>First Summary: Lateral Inversion in = Spatial=20 Hearing</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>On September, 2nd, I have put the = following query=20 on this list:</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>> I wonder if anybody on the = Auditory List knows=20 something about a lateral<BR>> inversion phenomenon I discovered when = preparing sounds for a series of<BR>> experiments on spatial hearing: = certain=20 binaural recordings of<BR>> bandpass-filtered clicks with interaural = time=20 differences but without<BR>> interaural intensity differences seem to = be=20 lateralized as predicted by<BR>> cross-correlation models in a = frequency=20 range below 2 Kilohertz but on the<BR>> opposite side than predicted = by these=20 models in a frequency range above<BR>> 8 Kilohertz.</FONT></DIV> <DIV> </DIV> <DIV><FONT face=3DArial size=3D2><FONT size=3D2><FONT face=3DArial>In = response to some=20 of your questions I have put an example sound file for the lateral = inversion=20 phenomenon on <A=20 href=3D"http://Heinrich.Zimmermann.com">http://Heinrich.Zimmermann.com</A= >.<BR></FONT></FONT></FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Thanks for the following = postings:</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Joachim Neubaum:<BR></FONT><FONT = face=3DArial=20 size=3D2>> In dem Buch<BR>> * J. Blauert<BR>> * R=E4umliches = H=F6ren<BR>>=20 * Monographien der Nachrichtentechnik, 1964 <BR>> steht was = =FCber=20 Lokalisation verschiedener Frequenzb=E4nder.<BR>> Das k=F6nnte = helfen, das von=20 Ihnen beobachtete Ph=E4nomen zu verstehen.<BR></FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Harry Erwin:</FONT></DIV> <DIV><FONT face=3DArial size=3D2>> I have a bat model that uses IIDs = to estimate=20 azimuth. I did this <BR>> because there's a tradeoff between = timing and=20 intensity (1 dB <BR>> corresponding to 47 microseconds of advance or = delay in=20 the Mexican <BR>> free-tailed bat, Pollak 1988), and the bat head is = too=20 small for ITDs <BR>> to work well at high frequencies (no more than = 40-50=20 microseconds in <BR>> E fuscus) while IIDs of 20-30 dB are seen due = to head=20 shadowing (see <BR>> Moss and Schnitzler in Popper and Fay, ed., = 1995,=20 Hearing by Bats, <BR>> Springer). At low frequencies (less than = about 3=20 kHz), the signal in <BR>> auditory nerve does track the variation, of = course,=20 and you can <BR>> do cross-correlation. My model works = beautifully for=20 a single target.<BR>> You may have seeing some sort of phenomenon = having to=20 do with the <BR>> time/intensity tradeoff. Assuming a head = diameter of=20 15 cm, you're <BR>> getting a ITD of about 750 microseconds at=20 most.</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Richard R Fabbri:</FONT></DIV> <DIV><FONT face=3DArial size=3D2>> What does the time domain waveform = (the=20 "click") exiting the<BR>> bandpass look like ?<BR>> Could you send = a=20 'scope trace ?<BR><BR>Daniel J. Tollin:</FONT></DIV> <DIV><FONT face=3DArial size=3D2>> Don't know if it is relevant to = your work or=20 not, but you might check out<BR>> the following paper:<BR>> Tollin = and=20 Henning (1999). Some aspects of the lateralization of echoed<BR>> = sound in=20 man. II. The role of the stimulus spectrum, J. Acoust. Soc. AM.<BR>> = 105,=20 838-849.<BR>> In that paper I describe a lateralization illusion in = which=20 observers<BR>> lateralize a signal opposite that expected based on = the ITD in=20 the signal.<BR>> I also give reasons for the anomalous=20 lateralization.<BR><BR>S. L. J. D. E. van de Par</FONT></DIV> <DIV><FONT face=3DArial size=3D2>> It is not entirely clear to me = what exactly=20 you observed,<BR>> but I assume that the clicks were lateralized to=20 one<BR>> side below 2 kHz and to the other side above 8 kHz <BR>> = (or was=20 it the case that they were lateralized to <BR>> the same = side but=20 that the models predicted otherwise?).<BR>> One thing came to mind = which may=20 be important.<BR>> When binaural stimuli are presented through=20 headphones<BR>> there may likely exist IIDs which vary as a = function<BR>>=20 of frequency due to differences in acoustic coupling of<BR>> the left = and=20 right earphones. These IIDs of course may<BR>> influence the = perceived=20 laterality. But I assume that you<BR>> have checked for = that.</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Ward Drennan</FONT></DIV> <DIV><FONT face=3DArial size=3D2>> I'd be suprised anything was = lateralized=20 without ILDs at 8KHz.</FONT></DIV> <DIV><FONT face=3DArial size=3D2>> Timing info is lost.<BR>> = An onset=20 asynchrony might give you a little cue, but I'd think in the<BR>> = direction=20 would be towards the leading filtered click. I don't know the<BR>>=20 bandwidths, the onset characteristics, the<BR>> delay times or the = precise=20 levels--- a 1 dB difference in level between the<BR>> left and right = ears=20 could give you a lateralization at 8 KHz-- expecially if<BR>> there = were no=20 onset asynchronies.</FONT></DIV></FONT></DIV></BODY></HTML> ------=_NextPart_000_00A2_01BF074A.9D685CE0--