Jacob Kirkegaard, Labyrinthitis (Touch)

“There are different types of “otoacoustic emissions” (OAEs): some are caused by random oscillations of the hair cells an arise spontaneously, others can be purposefully evoked by a specific acoustic stimulus that is sent into the ear from outside. When the ear is stimulated simultaneously with two pure tones at a frequency of f1 and f2, and if f1 and f2 are at a ratio of 1:1.2.this stimulation will create a distortion effect in the cochlea. The ear itself will generate a third tone at frequency f3, a so-called distortion product otoacoustic emission or DPOAE. (As DPOAEs will occur only when f1 and f2 are at a ratio of 1:1.2, the resulting f3 can always be calculated from the frequencies of the two tones that evoked it: f3=2f1-f2. Thus DPOAEs will also always be at a deeper frequency than their stimuli)”.