[Characteristics of 2F2-F1 distorsion products in adults with normal hearing]

Acoustic distorsion products (ADP) are otoemissions which the cochlea emits in response to stimulation by two pure frequencies, f1 and f2. ADP 2f1-f2 has been widely studied, however little work has been reported on ADP 2f2-f1. We performed a study in 34 adults with normal hearing to determine the normal values (incidence and amplitude) of ADP and compared them with the ADP 2f1-f2. Two f2/f1 ratios were used (1.22 and 1.12). Different behaviors were observed between the two types of ADP. These results suggest that the mechanisms generating the two ADP are different and that, consequently, ADP 2f2-f1 should have clinical implications different than ADP 2f1-f2.