With Labyrinthitis, Kirkegaard used otoacoustic emissions recorded with tiny speakers and microphones to capture the sounds generated by his inner ear. He then amplified these tones, and created a site-specific installation which produced otoacoustic emissions in the ears of the listeners.
These high frequency tones were looped and played through a series of speakers resembling the structure of the inner ear. The 16 speakers were attached to metal rods of varying lengths to create an ascending spiral hanging from a dome ceiling. The piece was first performed at the Medical Museum in Copenhagen, Denmark.
More info on the project with an in depth look at the project by Douglas Kahn here.
Also, a great review of the project by Manuel Arturo Abreu here.