The intensity-pitch relation revisited: monopolar versus bipolar cochlear stimulation.
OBJECTIVE
The very high speech perception scores now being achieved with cochlear implants have led to demands for similar levels of achievement in music perception and perception in noisy environments. One of the crucial factors in these fields is pitch perception. The aim of the present study was to investigate the extent to which pitch perception is influenced by the intensity of the stimulus, through the use of different stimulation modes (monopolar, bipolar) and different electrodes (lateral and perimodiolar).


METHODS
Sixteen postlingually deafened patients with an average implant use of 3.1 years were included in this study. All patients were using a Cochlear (CI24M, CI24R, CI24RE) cochlear implant.


METHODS
Subjects were asked to compare the pitch of an intensity-constant reference tone with the pitch of a test tone of varying intensity. The test was repeated for apical, mediocochlear, and basal channel locations, and also for monopolar and bipolar stimulation.


RESULTS
It was found that in monopolar stimulation 87.5% and in bipolar stimulation 85.7% of the patients perceived a clear pitch change with changing intensity of the stimulus (Spearman correlation coefficients r < -0.3 or r > 0.3, respectively). A total of 73.1% of these patients perceived lower pitches with increasing intensity, 26.9% reported the opposite effect. No statistically significant difference in the intensity-pitch correlation could be found between mono- and bipolar stimulation. Neither the mean dynamic range nor the type of electrode used was found to be related to the correlation coefficient.


CONCLUSIONS
Although the majority of today's cochlear implant recipients perform well and the intensity-pitch relation in cochlear implant recipients is still poorly understood, rising demands on speech-coding strategies may soon make a compensation of the pitch shifts desirable. Although the results of our study tend to argue against a peripheral mechanism, the exact origin of this phenomenon remains unclear.
Department of Otorhinolaryngology, Medical University of Vienna, Vienna, Austria.
Christoph
C
Arnoldner
Dominik
D
Riss
Alexandra
A
Kaider
Alois
A
Mair
Jens
J
Wagenblast
Wolf-Dieter
WD
Baumgartner
Wolfgang
W
Gstöttner
Jafar-Sasan
JS
Hamzavi
D000161:Acoustic Stimulation / Q000379:methods; D000293:Adolescent; D000328:Adult; D000368:Aged; D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D003638:Deafness / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010898:Pitch Perception / Q000502:physiology*; D011474:Prosthesis Design; D016896:Treatment Outcome