Distortion product OAEs (DPOAEs) represent cubic distortions of OHCs when stimulated simultaneously by two tones f1 (lower frequency) and f2 (higher frequency). DPOAEs arise directly from the frequency-selective compressive non- linearity of OHCs (Brownell et al., 1985, Kemp et al., 1986). The two tones interact in the cochlea close to the characteristic place of f2. Thus, DPOAEs can be applied as a probe for frequency-specific assessment of cochlear dysfunction at the f2 place. In humans the 2f1-f2 distortion component yields the highest amplitude and is therefore primarily used in audiological diagnostics (Gorga et al., 2000a). DPOAEs are reported to be measurable at a cochlear hearing-loss of up to 40-50 dB HL, representing approximately the range of the cochlear amplifier (Davis, 1983, Ruggero et al., 1997). TEOAEs and DPOAEs are present in essentially every normally hearing subject.
In Sentiero we offer two different DPOAE modules. DP Diagnostic and DP Threshold (patented method).