Otoacoustic Emissions Laboratory

Otoacoustic emissions are sounds generated by the ear in response to external stimulus sounds. The objectives of current studies in the Otoacoustic Emissions Laboratory are to better understand what otoacoustic emissions tell us about the workings of the cochlea and also how they may be better used in diagnostic tests of hearing.

Principal Investigator: Jonathan H. Siegel
j-siegel@northwestern.edu
Frances Searle Building 2-258
847-491-2454

Lab Project

Spatial origin of otoacoustic emissions in the cochlea. Otoacoustic emissions are sounds generated by the ear in response to external stimulus sounds. It is commonly assumed that these sounds are generated by the hair cells as a byproduct of their responses to the external stimulus sounds. They disappear in subjects with hearing loss resulting from loss of hair cells and this has led to objective screening tests for hearing loss. Since each frequency is detected most readily by a different region of the cochlea, it is also assumed that the otoacoustic emission sounds are generated in the region specific to the frequency of the emitted sound. However, our measurements of emissions from the ears of humans and chinchillas support another competing hypothesis that the emissions arise over a large region of the cochlea and this explains why it has been difficult to interpret the emissions. It also explains why the behavior of emissions corresponds only roughly to patterns of hearing loss. The objectives of our current studies are to better understand what otoacoustic emissions tell us about the workings of the cochlea and also how they may be better used in diagnostic tests of hearing.