AW: How good is inter-aural frequency or pitch matching in normal humans?

[Mathias Dietz <mathias.dietz@xxxxxxxxxxxxxxxx>]

Dear Jan, dear List,
This is a cool and interesting observation.
We have recently finished a study on bilateral CI subjects from which two things may be relevant for you:
1) The electrodes that provide the same frequency band (typically electrodes with the same number) are nicely place-pitch matched in all subjects we measured. The maximum deviation is 1 electrode. This is presumably better than the actual place-of-stimulation match (which was not measured directly). We hypothesize that acclimatization / adaptation to the clinical electrode-frequency map is the reason. This is not in contradiction with your report, because we are not accurate enough to detect a difference corresponding to a semitone.
2) ITD sensitivity is not optimal for pitch matched electrodes. There are subjects which have no measureable ITD sensitivity for pitch matched electrodes but >80% correct if you move 4-5 mm away.
>From the above I would say that there is no contradiction between the observation of your conversation partner and the assumption “that there has to be a good alignment of frequency channels going into the binaural centers of the brainstem”. Pitch does not require this alignment nor has it been shown to be a very good indicator. 
That still does not explain the different interaural pitch percept for your acoustic hearing listener so I pass on to the next…
Best,
Mathias


-- 
Dr. Mathias Dietz
Medizinische Physik
and Cluster of Excellence Hearing4all 
Universität Oldenburg
D - 26111 Oldenburg
Tel. (+49) 441 798 5472
Email: mathias.dietz@xxxxxxxxxxxxxxxx
WWW: http://medi.uni-oldenburg.de/52096.html
Profil: http://medi.uni-oldenburg.de/members/mathias.dietz


Von: AUDITORY - Research in Auditory Perception [mailto:AUDITORY@xxxxxxxxxxxxxxx] Im Auftrag von Jan Schnupp
Gesendet: Montag, 29. Juni 2015 15:45
An: AUDITORY@xxxxxxxxxxxxxxx
Betreff: How good is inter-aural frequency or pitch matching in normal humans?

Dear List,

I have had a conversation with a musically keen retired physicist who assured me that when he holds up a tuning fork to one ear he hears the pitch of the tuning fork about a semitone lower than at the other ear. I had to say that I found that surprising. We always assume that there has to be a good alignment of frequency channels going into the binaural centers of the brainstem for example, and much effort is invested in trying to improve "inter-aural pitch matching" for cochlear implant patients. But I have to admit I know of no formal studies that have actually measured how good inter-aural pitch matching would be for normally hearing subjects, and whether a difference of a semitone (after all, only a few % in absolute terms) is absurdly large or within the expected human variability. Would any of you know of any papers that have looked at this?

Best,

Jan 


-- 
Prof Jan Schnupp
University of Oxford
Dept. of Physiology, Anatomy and Genetics
Sherrington Building - Parks Road
Oxford OX1 3PT - UK
+44-1865-282012
http://jan.schnupp.net