Subject: Re: [AUDITORY] Sensitivity to ITDs with mismatched frequencies in From: Dan Ellis <dan.ellis@xxxxxxxx> Date: Wed, 24 Feb 2021 09:48:35 -0500--000000000000352de105bc1621eb Content-Type: text/plain; charset="UTF-8" I don't know any relevant psychophysics, but it strikes me that at some point you are going to push against time-frequency uncertainty. A "gabor click" contains only a few cycles of its center frequency in the time domain, which is equivalent to the Gaussian "blur" of its spectrum. This makes it hard to even recognize a difference in frequency regardless of ITD comparison. So a simpler question might be what the frequency jnd is for short bandpass-filtered clicks, which at some point will be limited by the bandwidth. I would certainly recommend looking at the actual waveforms of the pulses you're using for insight into the underlying nature of the task, as well as taking care over the precise phase relationship of envelope and carrier. DAn. SN. On Wed, Feb 24, 2021 at 5:47 AM Jan Schnupp < 000000e042a1ec30-dmarc-request@xxxxxxxx> wrote: > Dear List, > > I am curious if you could recommend some reading for me. We have been > increasingly interested in ITD coding with cochlear implants and have > developed a nice little animal model which shows a surprisingly robust > behavioral ITD sensitivity even if deafened in infancy and only implanted > in young adulthood. > One question we often get and which we would like to investigate is: how > much does it matter if there is a bit of a mismatch between the frequency > channels in the left and right ears? How badly do they have to be > mismatched before ITD sensitivity disappears? > I kind of assumed that there must have been a lot of psychoacoustics on > this, at least in normally hearing human subjects. Of course at low > frequencies, if you mismatch the left and right ears you get binaural > beats, but what about envelope ITDs? You could deliver for example trains > of short gabor clicks to each ear with a greater or lesser extent of > carrier frequency mismatch, and see how the mismatch affects ITD > thresholds. It seems like such an obvious thing to try, surely somebody > must have done this or something similar? But a quick look on google > scholar didn't yield very much. A modelling paper by Bonham and Lewis 1999 > was the top hit. I haven't seen much in the way of data. Surely I must be > missing something...? Any suggestions for relevant reading > gratefully accepted. > > Best wishes, > > Jan > > > --------------------------------------- > Prof Jan Schnupp > City University of Hong Kong > Dept. of Neuroscience > 31 To Yuen Street, > Kowloon Tong > Hong Kong > > https://auditoryneuroscience.com > http://jan.schnupp.net > --000000000000352de105bc1621eb Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr">I don't know any relevant psychophysics, but it strike= s me that at some point you are going to push against time-frequency uncert= ainty.=C2=A0 A "gabor click" contains only a few cycles of its ce= nter frequency in the time domain, which is equivalent to the Gaussian &quo= t;blur" of its spectrum.=C2=A0 This makes it hard to even recognize a = difference in frequency regardless of ITD comparison.=C2=A0 So a simpler qu= estion might be what the frequency jnd is for short bandpass-filtered click= s, which at some point will be limited by the bandwidth.=C2=A0 I would cert= ainly recommend looking at the actual waveforms of the pulses you're us= ing for insight into the underlying nature of the task, as well as taking c= are over the precise phase relationship of envelope and carrier.<div><br></= div><div>=C2=A0 DAn.<br><div><br></div><div>=C2=A0 SN.</div></div></div><br= ><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On Wed, F= eb 24, 2021 at 5:47 AM Jan Schnupp <<a href=3D"mailto:000000e042a1ec30-d= marc-request@xxxxxxxx">000000e042a1ec30-dmarc-request@xxxxxxxx= a</a>> wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin= :0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-lef= t-color:rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr">Dear List,<div>= <br></div><div>I am curious if you could recommend some reading for me. We = have been increasingly interested in ITD coding with cochlear implants and = have developed a nice little animal model which shows a surprisingly robust= behavioral ITD sensitivity even if deafened in infancy and only implanted = in young adulthood.=C2=A0</div><div>One question we often get and which we = would like to investigate is: how much does it matter if there is a bit of = a mismatch between the frequency channels in the left and right ears? How b= adly do they have to be mismatched before ITD sensitivity disappears?</div>= <div>I kind of assumed that there must have been a lot of psychoacoustics o= n this, at least in normally hearing human subjects. Of course at low frequ= encies, if you mismatch the left and right ears you get binaural beats, but= what about envelope ITDs?=C2=A0You could deliver for example trains of sho= rt gabor clicks to each ear with a greater or lesser extent of carrier freq= uency mismatch, and see how the=C2=A0mismatch affects ITD thresholds. It se= ems like such an obvious thing to try, surely somebody must have done this = or something similar? But a quick look on google scholar didn't yield v= ery much. A modelling paper by Bonham and Lewis 1999 was the top hit. I hav= en't seen much in the way of data. Surely I must be missing something..= .? Any suggestions for relevant reading gratefully=C2=A0accepted.=C2=A0</di= v><div><br></div><div>Best wishes,</div><div><br></div><div>Jan</div><div><= br clear=3D"all"><div><div dir=3D"ltr"><div dir=3D"ltr"><div><div dir=3D"lt= r"><div><div dir=3D"ltr"><div dir=3D"ltr"><div dir=3D"ltr"><div dir=3D"ltr"= ><div style=3D"font-size:12.8px"><br></div><div style=3D"font-size:12.8px">= ---------------------------------------</div><div style=3D"font-size:12.8px= ">Prof Jan Schnupp<br>City University of Hong Kong<br>Dept. of Neuroscience= </div><div><div style=3D"font-size:12.8px">31 To Yuen Street,=C2=A0</div><d= iv style=3D"font-size:12.8px"><span style=3D"font-size:12.8px">Kowloon Tong= </span></div><div style=3D"font-size:12.8px">Hong Kong</div><div style=3D"f= ont-size:12.8px"><br></div><a href=3D"https://auditoryneuroscience.com" tar= get=3D"_blank">https://auditoryneuroscience.com</a></div><div><a href=3D"ht= tp://jan.schnupp.net" target=3D"_blank">http://jan.schnupp.net</a></div></d= iv></div></div></div></div></div></div></div></div></div></div></div> </blockquote></div> --000000000000352de105bc1621eb--