Time-intensity trading in bilateral congenital aural atresia patients.
In an effort to examine the rules by which information of bilaterally applied bone-conducted signals arising from interaural time differences (ITD) and interaural intensity differences (IID) is combined, data were measured for continuous 500 Hz narrow band noise at 65-70 dB HL in 11 patients with bilateral congenital aural atresia. Time-intensity trading functions were obtained by shifting the sound image towards one side using ITD, and shifting back to a centered sound image by varying the IID in the same ear (auditory midline task). ITD values were varied from -600 to +600 micros at 200 micros steps, where negative values indicate delays to the right ear. The results indicate that time-intensity trading is present in patients with bilateral aural atresia. The gross response properties of time-intensity trading in response to bone-conducted signals were comparable in patients with bilateral aural atresia and normal-hearing subjects, though there was a larger inter-subject variability and higher discrimination thresholds across IIDs in the atresia group. These results suggest that the mature auditory brainstem has a potential to employ binaural cues later in life, although to a restricted degree. A binaural fitting of a bone-conducted hearing aid might optimize binaural hearing and improve sound lateralization, and we recommend now systematically bilateral fitting in aural atresia patients.
Schmerber
Sébastien
S
Department of Otolaryngology, University Hospital, Service O.R.L C.H.U de Grenoble, France. sschmerber@chu-grenoble.fr
Sheykholeslami
Kianoush
K
Kermany
Mohammad Habiby
MH
Hotta
Shoko
S
Kaga
Kimitaka
K
D000161:Acoustic Stimulation / Q000379:methods; D000293:Adolescent; D001309:Auditory Threshold; D001844:Bone Conduction; D016022:Case-Control Studies; D004192:Discrimination, Psychological; D004423:Ear / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D009622:Noise; D013017:Sound Localization; D013997:Time Factors; D014057:Tomography, X-Ray Computed