1. עבוד אותות במערכת החושים סמסטר א' תשס"ז http://www.eng.tau.ac.il/~mira/senseses2006 Cochlear Implant Binaural Hearing http://www.eng.tau.ac.il/~mira/senseses2006

2. Cochlear Implant

3. 1. Sound Processor captures sound from the environment processes sound into digital information transmits to the implant over a transmitting antenna, or headpiece, held in place by magnets in both the headpiece and implant 2. Implant converts digital information into electrical signals sends signals down tiny wires to the electrode array in the inner ear delivers electrical signals through tiny contacts, or electrodes, to the hearing nerve the hearing nerve carries the sound information to the brain, where it is heard 3. Electrode Array

5. Localization = judgment of the direction and distance of a sound source Lateralization = the apparent location of the sound source within the head when headphones are used

6. Binaural Hearing: Interaural Differences We will conduct an experiment to measure the minimum ILD/ITD. t Left, L Left t Right, L Right

7. Masking Level Difference MLD=0 dB MLD=15 dB MLD=0 dB MLD=9dB

9. The Pina

10. Head Related Transfer Function

11. “”Cone of confusion בתוך הקונוס התלת ממדי ישנם צרופים שונים של מקומות שלהם יש אותו ITD ואותו ILD היוצרים אזור של קושי בהחלטה של מיקום הקול. תנועות הראש משנות את מיקום הקונוס ומקטינות את אזור חוסר הוודאות

12. Minimal Audible Angle - MAA מהו ההפרש הקטן ביותר בשינוי מיקום הקול המאפשר הבחנה בשינוי זה ? היכולת שלנו להבחין בהפרש במיקום מקור הקול היא טובה ביותר כשהקול מגיע מלפנים בחזית הראש. יכולת זו הולכת ופוחתת כשמקור הקול נמצא בצדי הראש או מאחור. שינויים קטנים בכיוון הקול מלפנים יוצרים הבדלים גדולים ב - ITD.

13. LATERALIZATION 1 5 9 2 3 4 8 6 7 Perception Stimulus R L R R L L ILD ITD ITD=ILD=0

14. Histograms = number of times a subject reported perceiving a position when ITD or ILD presented Normal Performance

15. 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 -110 0-10 0 1 -1 1 2 3 4 5 6 7 8 9 -10 010 1 2 3 4 5 6 7 8 9 Center-OrientedSide --Oriented position ITD(msec) ILD(dB) Abnormal Performance

16. Patients’ Performance

17. Auditory Pathway in the Human Brain

18. Neural Response to Interaural Differences

19. Lesion Detection on MRI Scans

20. Brainstem MRI Scans AxialCoronal Sagittal

21. Auditory Pathway in the Human Brain

22. Schematic Representation of the Brainstem Auditory Pathway

23. Auditory Pathway and Brainstem Outline Overlapped on fMRI Scans

24. Lesion Detection

25. Overlap of Auditory Pathway on MRI Scans

26. Correlation between MRI and Lateralization Normal Lateralization MS10 MS20 MS50 MS52 CVA23

27. Correlation between MRI and Lateralization Side-Oriented Lateralization

28. Correlation between MRI and Lateralization Center-Oriented Lateralization

29. Correlation between MRI and Lateralization

30. Experimental Summary and Conclusions Two types of abnormal lateralization performance were found : center-oriented and side-oriented. Both types of abnormalities were found in patients with either MS or Stroke Center-oriented lateralization is correlated with TB/SOC lesions Side-oriented lateralization is correlated with LL/IC lesions

31. fMRI Study with Binaural Stimulation Coronal cut (2/11) - MGBAxial cut (6/12) -SOC Axial cut (10/12) - LL Axial cut (2/12) - CN 0 0.025 Coronal cut (6/11) - AC

32. Monaural & Binaural Activation in a Right Sagittal Section Left Ear Stimulation Right & Left Ears Stimulation Right Ear Stimulation

33. Monaural & Binaural Activation in a Left Sagittal Section Left ear stimulation Both ears stimulation Right ear stimulation

34. Interaural Discrimination A model that correctly estimates the human’s ability to distinguish between azimuth of two close identical tone signals. t Left, L Left t Right, L Right ITD = t Right – t Left [Sec] ILD = L Right – L Left [dB] Min(ITD)=? ~20µSec Min(ILD)=? ~1dB

35. Experimental results Time JND [µSec]Level JND [dB]

36. Simulation results N =32N =2 Time JND [µSec]Level JND [dB] Simulation Mean of Experimental results