Introduction One objective of the presented study is the validation of positron emission tomography (PET) as an examination method for mono- and binaural speech recognition. In the present intermediate evaluation we report results of the normal-hearing control group.
Methods Using PET and injection of O-15 water, the central auditory pathway was examined in 7 normal-hearing subjects under 4 different stimulation conditions. As stimuli, sets of the Oldenburg sentence test (OLSA) were presented in the original version and as non-semantic controls with comparable frequency spectrum and dynamic range played backwards; unilaterally on the right and bilaterally. The PET scans were evaluated after stereotactic normalization and global normalization of the count rate by SPM.
Results With 3 PET measurements per stimulation condition, a total of 83 PET scans were analysed (1 missing measurement: synthesis failure). There was a significant increase in perfusion in the right primary auditory cortex with bilateral stimulation compared to unilateral right side stimulation with left ear masked. In forward presentation of the sentences there is an increase in perfusion in the Wernicke region (posterior Brodmann area 22 left) compared to the backward presentation.
Discussion In the present validation study, we were able to demonstrate significant changes in perfusion in the expected cortex areas by comparing uni- and bilateral as well as semantic and non-semantic stimulus presentation. The method presented may therefore be appropriate for the investigation of neuronal processes in speech recognition in CI recipients. Currently, single-sided deaf CI recipients are currently examined with the validated method.
Forschungskommission des Universitätsklinikum Freiburg und dem Fördervrein "Taube Kinder lernen Hören"
Poster-PDF
A-1323.PDF
