Acoustic Distortion Products (Shift-OAE)


This measure, based on the collection of distortion products, records the response time of external ciliate cells of the cochlea. Our exclusive clinical studies have shown that the measured time is the image of the pressure in the perilymph (apex). Monitoring Shift-OAE can observe reproducible or isolated pressure changes from the cochlea and thus highlight a cochlear hydrops.


User tips: 

Measure specifications:


Aimed Diseases


Method :

In the case of record of distortion products, bitonal acoustic stimulation is applied (simultaneous sending of two pure tones). These two sounds exciting, called primary, with the respective frequencies f1 and f2 will cause the emission of a characteristic distortion product in human beeing at frequency 2f1-f2. In healthy subjects as subjects with endolymphatic hydrops, postural tests, (from standing to lying position) cause an increase of intra-cochlear pressure (exaggerated in the context of Meniere's disease). Indeed, during postural tests there is a change in the distribution of cerebrospinal fluid that spreads to the cochlea via the cochlear aqueduct.

Monitored, the cochlear physiological parameter allows real time monitoring of the evolution of intra-cochlear pressure.


Echodia device allowing Shift-OAE measurements: ELIOS.