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Re: [AUDITORY] Sensitivity to ITDs with mismatched frequencies in each ear?



Yes, it sure does seem like someone would have tested that by now. 

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Blanks DA, Buss E, Grose JH, Fitzpatrick DC, Hall JW 3rd. Interaural time discrimination of envelopes carried on high-frequency tones as a function of level and interaural carrier mismatch. Ear Hear. 2008;29(5):674-683. doi:10.1097/AUD.0b013e3181775e03

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2648125/


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Goupell MJ, Stoelb C, Kan A, Litovsky RY. Effect of mismatched place-of-stimulation on the salience of binaural cues in conditions that simulate bilateral cochlear-implant listening. J Acoust Soc Am. 2013;133(4):2272-2287. doi:10.1121/1.4792936

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3631247/



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Kan A, Litovsky RY, Goupell MJ. Effects of interaural pitch matching and auditory image centering on binaural sensitivity in cochlear implant users. Ear Hear. 2015;36(3):e62-e68. doi:10.1097/AUD.0000000000000135

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4409917/


-Chris


:-)



On Feb 24, 2021, at 3:45 AM, Jan Schnupp <000000e042a1ec30-dmarc-request@xxxxxxxxxxxxxxx> 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