hearing instrument specialist

i think the course that is closer to your major is Speech and Hearing offered by
the University of Hong Kong (under the Faculty of Education).
you may find some information about this course here :
http://www.hku.hk/speech/

most graduates became speech therapists and were employed by schools,
clinics, hospitals etc... some became research assistants.
here are some stats that i found on the internet, with a list of employers
and job titles (it's the stat of last year's graduates, the list is just to give
you some ideas...)
http://www.hku.hk/cepc/leaflet2005/pdf/FD/BSc(Sp&HearSc).pdf

and HKU does offer a Master of Science in Audiology, which is your major :
http://www.hku.hk/education/msc(audiology)_all.htm

some of the job listings of the 2000 graduates in this Msc :
http://www.hku.hk/cepc/leaflet2000/HigherDegree/Education/MSc(Audiology).html
1998 graduates:
http://www.hku.hk/cepc/leaf98/MSc(Audiology)/MSc(Audiology).pdf