Distortion products are characterized by two stimulating sounds known as primaries. By varying the frequencies of these two primaries f1 and f2, it is possible to collect various distortion products to get a tracing called DPgram (graphic distortion products, analogy to the audiogram). By observing the spectrum cochlear, frequency by frequency (1000 to 32 000Hz), it is possible to estimate the degree of deafness.
The OtoPhyLab device integrates high frequencies ranges in order to scan the major part of the animal cochlea.